Method and apparatus for transmitting and receiving signal in wireless communication system

ABSTRACT

A method of transmitting and receiving a signal in a wireless communication system and an apparatus supporting the method are disclosed.

TECHNICAL FIELD

The present disclosure relates to a method and apparatus fortransmitting and receiving a signal in a wireless communication system.

BACKGROUND ART

Wireless access systems have been widely deployed to provide varioustypes of communication services such as voice or data. In general, awireless access system is a multiple access system that supportscommunication of multiple users by sharing available system resources (abandwidth, transmission power, etc.) among them. For example, multipleaccess systems include a code division multiple access (CDMA) system, afrequency division multiple access (FDMA) system, a time divisionmultiple access (TDMA) system, an orthogonal frequency division multipleaccess (OFDMA) system, and a single carrier frequency division multipleaccess (SC-FDMA) system.

DISCLOSURE Technical Problem

Provided are a method and apparatus for efficiently performing awireless signal transmission and reception procedure.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present disclosure are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present disclosure could achieve will be more clearlyunderstood from the following detailed description.

Technical Solution

In one aspect of the present disclosure, a method of a user equipment(UE) in a wireless communication system includes receiving systeminformation, acquiring a channel access mode based on the systeminformation, performing a channel access procedure (CAP) based on thechannel access mode, and transmitting an uplink signal based on a resultof the CAP. The channel access mode includes a first mode and a secondmode, a CAP type of the first mode is difference from a CAP type of thesecond mode, and the acquired channel access mode is i) a channel accessmode indicated by the system information between the first mode and thesecond mode based on the system information including information aboutthe channel access mode, or ii) the first mode based on the systeminformation not including the information about the channel access mode.

In another aspect of the present disclosure, a UE in a wirelesscommunication system includes at least one transceiver, at least oneprocessor, and at least one computer memory operatively coupled to theat least one transceiver and at least one processor and, when executed,causing the at least one transceiver and at least one processor toperform operations. The operations include receiving system information,acquiring a channel access mode based on the system information,performing a CAP based on the channel access mode, and transmitting anuplink signal based on a result of the CAP. The channel access modeincludes a first mode and a second mode, a CAP type of the first mode isdifference from a CAP type of the second mode, and the acquired channelaccess mode is i) a channel access mode indicated by the systeminformation between the first mode and the second mode based on thesystem information including information about the channel access mode,or ii) the first mode based on the system information not including theinformation about the channel access mode.

In another aspect of the present disclosure, an apparatus for a UEincludes at least one processor, and at least one computer memoryoperatively coupled to the at least one processor and, when executed,causing the at least one processor to perform operations. The operationsinclude receiving system information, acquiring a channel access modebased on the system information, performing a CAP based on the channelaccess mode, and transmitting an uplink signal based on a result of theCAP. The channel access mode includes a first mode and a second mode, aCAP type of the first mode is difference from a CAP type of the secondmode, and the acquired channel access mode is i) a channel access modeindicated by the system information between the first mode and thesecond mode based on the system information including information aboutthe channel access mode, or ii) the first mode based on the systeminformation not including the information about the channel access mode.

In another aspect of the present disclosure, a processor-readable mediumstores one or more instructions which, when executed, cause at least oneprocessor to perform operations. The operations include receiving systeminformation, acquiring a channel access mode based on the systeminformation, performing a CAP based on the channel access mode, andtransmitting an uplink signal based on a result of the CAP. The channelaccess mode includes a first mode and a second mode, a CAP type of thefirst mode is difference from a CAP type of the second mode, and theacquired channel access mode is i) a channel access mode indicated bythe system information between the first mode and the second mode basedon the system information including information about the channel accessmode, or ii) the first mode based on the system information notincluding the information about the channel access mode.

The CAP type of the first mode may include a random backoff-based CAP.

The second mode may be a mode in which the CAP and the signaltransmission are performed in a period of a specific length based on astructure of periodically repeating the period of the specific length.

The CAP type of the first mode may further include a CAP in which it isdetermined whether a channel is idle during a predetermined first timeperiod, and the CAP type of the second mode may be a CAP in which it isdetermined whether a channel is idle for a predetermined second timeperiod.

The length of the first time period may be larger than the length of thesecond time period.

The second time period may be included in the period of the specificlength.

The UL signal may include a physical random access channel (PRACH), andbased on an RACH occasion (RO) being configured as a boundary of theperiod of the specific length, the PRACH may be transmitted in the RObased on the result of the CAP regardless of whether a downlink signalhas been detected in the period of the specific length.

The uplink signal may include an uplink signal not requiring an uplinkgrant, the period of the specific length is configured for each of abase station (BS) and the UE, and the uplink signal may be transmittedin the period of the specific length based on the result of the CAP,based on a downlink signal not being received in the period of thespecific length configured for the UE.

The uplink signal may be transmitted in an unlicensed band.

An apparatus applied to an embodiment of the present disclosure mayinclude an autonomous driving vehicle.

The above-describe aspects of the present disclosure are merely a partof preferred embodiments of the present disclosure, and those skilled inthe art will derive and understand various embodiments reflectingtechnical features of the present disclosure based on the followingdetailed description of the present disclosure.

Advantageous Effects

According to embodiments of the present disclosure, a signal may beefficiently transmitted and received in a wireless communication system.

According to embodiments of the present disclosure, an efficient signaltransmission method considering the characteristics of an unlicensedband is provided.

According to embodiments of the present disclosure, information about achannel access mode supported in an unlicensed band may be efficientlyacquired.

It will be appreciated by persons skilled in the art that the effectsthat can be achieved with the present disclosure are not limited to whathas been particularly described hereinabove and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure, illustrate embodiments of thedisclosure and together with the description serve to explain theprinciple of the disclosure.

In the drawings:

FIG. 1 illustrates physical channels and a general signal transmissionmethod using the physical channels in a 3^(rd) generation partnershipproject (3GPP) system as an exemplary wireless communication system;

FIG. 2 illustrates a radio frame structure;

FIG. 3 illustrates a resource grid during the duration of a slot;

FIG. 4 illustrates exemplary mapping of physical channels in a slot;

FIG. 5 illustrates exemplary uplink (UL) transmission operations of auser equipment (UE);

FIG. 6 illustrates exemplary repeated transmissions based on aconfigured grant;

FIG. 7 illustrates a wireless communication system supporting anunlicensed band;

FIG. 8 illustrates an exemplary method of occupying resources in anunlicensed band;

FIG. 9 illustrates an exemplary channel access procedure of a UE for ULsignal transmission in an unlicensed band applicable to the presentdisclosure;

FIGS. 10 and 11 illustrate exemplary time resources for channel accessmodes according to an embodiment of the present disclosure;

FIGS. 12 and 13 illustrate a signal transmission process according to anembodiment of the present disclosure;

FIG. 14 illustrates an exemplary communication system applied to thepresent disclosure;

FIG. 15 illustrates an exemplary wireless device applicable to thepresent disclosure;

FIG. 16 illustrates another exemplary wireless device applicable to thepresent disclosure; and

FIG. 17 illustrates an exemplary vehicle or autonomous driving vehicleapplicable to the present disclosure.

BEST MODE

The following technology may be used in various wireless access systemssuch as code division multiple access (CDMA), frequency divisionmultiple access (FDMA), time division multiple access (TDMA), orthogonalfrequency division multiple access (OFDMA), single carrier frequencydivision multiple access (SC-FDMA), and so on. CDMA may be implementedas a radio technology such as universal terrestrial radio access (UTRA)or CDMA2000. TDMA may be implemented as a radio technology such asglobal system for mobile communications (GSM)/general packet radioservice (GPRS)/enhanced data rates for GSM evolution (EDGE). OFDMA maybe implemented as a radio technology such as institute of electrical andelectronics engineers (IEEE) 802.11 (wireless fidelity (Wi-Fi)), IEEE802.16 (worldwide interoperability for microwave access (WiMAX)), IEEE802.20, evolved UTRA (E-UTRA), and so on. UTRA is a part of universalmobile telecommunications system (UMTS). 3^(rd) generation partnershipproject (3GPP) long term evolution (LTE) is a part of evolved UMTS(E-UMTS) using E-UTRA, and LTE-advanced (LTE-A) is an evolution of 3GPPLTE. 3GPP new radio or new radio access technology (NR) is an evolvedversion of 3GPP LTE/LTE-A.

As more and more communication devices require larger communicationcapacities, the need for enhanced mobile broadband communicationrelative to the legacy radio access technologies (RATs) has emerged.Massive machine type communication (MTC) providing various services tointer-connected multiple devices and things at any time in any place isone of significant issues to be addressed for next-generationcommunication. A communication system design in which services sensitiveto reliability and latency are considered is under discussion as well.As such, the introduction of the next-generation radio access technology(RAT) for enhanced mobile broadband communication (eMBB), massive MTC(mMTC), and ultra-reliable and low latency communication (URLLC) isbeing discussed. For convenience, this technology is called NR or NewRAT in the present disclosure.

While the following description is given in the context of a 3GPPcommunication system (e.g., NR) for clarity, the technical spirit of thepresent disclosure is not limited to the 3GPP communication system. Forthe background art, terms, and abbreviations used in the presentdisclosure, refer to the technical specifications published before thepresent disclosure (e.g., 38.211, 38.212, 38.213, 38.214, 38.300,38.331, and so on).

In a wireless access system, a user equipment (UE) receives informationfrom a base station (BS) on DL and transmits information to the BS onUL. The information transmitted and received between the UE and the BSincludes general data and various types of control information. Thereare many physical channels according to the types/usages of informationtransmitted and received between the BS and the UE.

FIG. 1 illustrates physical channels and a general signal transmissionmethod using the physical channels in a 3GPP system.

When a UE is powered on or enters a new cell, the UE performs initialcell search (S11). The initial cell search involves acquisition ofsynchronization to a BS. For this purpose, the UE receives asynchronization signal block (SSB) from the BS. The SSB includes aprimary synchronization signal (PSS), a secondary synchronization signal(SSS), and a physical broadcast channel (PBCH). The UE synchronizes itstiming to the BS and acquires information such as a cell identifier (ID)based on the PSS/SSS. Further, the UE may acquire information broadcastin the cell by receiving the PBCH from the BS. During the initial cellsearch, the UE may also monitor a DL channel state by receiving adownlink reference signal (DL RS).

After the initial cell search, the UE may acquire more detailed systeminformation by receiving a physical downlink control channel (PDCCH) anda physical downlink shared channel (PDSCH) corresponding to the PDCCH(S12).

Subsequently, to complete connection to the BS, the UE may perform arandom access procedure with the BS (S13 to S16). Specifically, the UEmay transmit a preamble on a physical random access channel (PRACH)(S13) and may receive a PDCCH and a random access response (RAR) for thepreamble on a PDSCH corresponding to the PDCCH (S14). The UE may thentransmit a physical uplink shared channel (PUSCH) by using schedulinginformation in the RAR (S15), and perform a contention resolutionprocedure including reception of a PDCCH and a PDSCH signalcorresponding to the PDCCH (S16).

When the random access procedure is performed in two steps, steps S13and S15 may be performed as one step (in which Message A is transmittedby the UE), and steps S14 and S16 may be performed as one step (in whichMessage B is transmitted by the BS).

After the above procedure, the UE may receive a PDCCH and/or a PDSCHfrom the BS (S17) and transmit a physical uplink shared channel (PUSCH)and/or a physical uplink control channel (PUCCH) to the BS (S18), in ageneral UL/DL signal transmission procedure. Control information thatthe UE transmits to the BS is generically called uplink controlinformation (UCI). The UCI includes a hybrid automatic repeat andrequest acknowledgement/negative acknowledgement (HARQ-ACK/NACK), ascheduling request (SR), channel state information (CSI), and so on. TheCSI includes a channel quality indicator (CQI), a precoding matrix index(PMI), a rank indication (RI), and so on. In general, UCI is transmittedon a PUCCH. However, if control information and data should betransmitted simultaneously, the control information and the data may betransmitted on a PUSCH. In addition, the UE may transmit the UCIaperiodically on the PUSCH, upon receipt of a request/command from anetwork.

FIG. 2 illustrates a radio frame structure.

In NR, UL and DL transmissions are configured in frames. Each radioframe has a length of 10 ms and is divided into two 5-ms half-frames.Each half-frame is divided into five 1-ms subframes. A subframe isdivided into one or more slots, and the number of slots in a subframedepends on a subcarrier spacing (SCS). Each slot includes 12 or 14OFDM(A) symbols according to a cyclic prefix (CP). When a normal CP isused, each slot includes 14 OFDM symbols. When an extended CP is used,each slot includes 12 OFDM symbols. A symbol may include an OFDM symbol(or a CP-OFDM symbol) and an SC-FDMA symbol (or a discrete Fouriertransform-spread-OFDM (DFT-s-OFDM) symbol).

Table 1 exemplarily illustrates that the number of symbols per slot, thenumber of slots per frame, and the number of slots per subframe varyaccording to SCSs in a normal CP case.

TABLE 1 SCS (15*2{circumflex over ( )}u) N^(slot) _(symb) N^(frame, u)_(slot) N^(subframe, u) _(slot) 15 KHz (u = 0) 14 10 1 30 KHz (u = 1) 1420 2 60 KHz (u = 2) 14 40 4 120 KHz (u = 3) 14 80 8 240 KHz (u = 4) 14160 16 *N^(slot) _(symb): number of symbols in a slot *N^(frame, u)_(slot): number of slots in a frame *N^(subframe, u) _(slot): number ofslots in a subframe

Table 2 illustrates that the number of symbols per slot, the number ofslots per frame, and the number of slots per subframe vary according toSCSs in an extended CP case.

TABLE 2 SCS (15*2{circumflex over ( )}u) N^(slot) _(symb) N^(frame, u)_(slot) N^(subframe, u) _(slot) 60 KHz (u = 2) 12 40 4The frame structure is merely an example, and the number of subframes,the number of slots, and the number of symbols in a frame may be changedin various manners.

In the NR system, different OFDM(A) numerologies (e.g., SCSs, CPlengths, and so on) may be configured for a plurality of cellsaggregated for one UE. Accordingly, the (absolute time) duration of atime resource (e.g., a subframe, a slot, or a transmission time interval(TTI)) (for convenience, referred to as a time unit (TU)) composed ofthe same number of symbols may be configured differently between theaggregated cells.

In NR, various numerologies (or SCSs) may be supported to supportvarious 5th generation (5G) services. For example, with an SCS of 15kHz, a wide area in traditional cellular bands may be supported, whilewith an SCS of 30 kHz or 60 kHz, a dense urban area, a lower latency,and a wide carrier bandwidth may be supported. With an SCS of 60 kHz orhigher, a bandwidth larger than 24.25 kHz may be supported to overcomephase noise.

An NR frequency band may be defined by two types of frequency ranges,FR1 and FR2. 1-R1 and FR2 may be configured as described in Table 3below. FR2 may be millimeter wave (mmW).

TABLE 3 Frequency Range Corresponding designation frequency rangeSubcarrier Spacing FR1  450 MHz-7125 MHz 15, 30, 60 kHz FR2 24250MHz-52600 MHz 60, 120, 240 kHz

FIG. 3 illustrates a resource grid during the duration of one slot.

A slot includes a plurality of symbols in the time domain. For example,one slot includes 14 symbols in a normal CP case and 12 symbols in anextended CP case. A carrier includes a plurality of subcarriers in thefrequency domain. A resource block (RB) may be defined by a plurality of(e.g., 12) consecutive subcarriers in the frequency domain. A bandwidthpart (BWP) may be defined by a plurality of consecutive (physical) RBs((P)RBs) in the frequency domain and correspond to one numerology (e.g.,SCS, CP length, and so on). A carrier may include up to N (e.g., 5)BWPs. Data communication may be conducted in an active BWP, and only oneBWP may be activated for one UE. Each element in a resource grid may bereferred to as a resource element (RE), to which one complex symbol maybe mapped.

FIG. 4 illustrates exemplary mapping of physical channels in a slot.

A DL control channel, DL or UL data, and a UL control channel may all beincluded in one slot. For example, the first N symbols (hereinafter,referred to as a DL control region) in a slot may be used to transmit aDL control channel, and the last M symbols (hereinafter, referred to asa UL control region) in the slot may be used to transmit a UL controlchannel. N and M are integers equal to or greater than 0. A resourceregion (hereinafter, referred to as a data region) between the DLcontrol region and the UL control region may be used for DL datatransmission or UL data transmission. A time gap for DL-to-UL orUL-to-DL switching may be defined between a control region and the dataregion. A PDCCH may be transmitted in the DL control region, and a PDSCHmay be transmitted in the DL data region. Some symbols at the time ofswitching from DL to UL in a slot may be configured as the time gap.

Now, a detailed description will be given of physical channels.

The PDSCH delivers DL data (e.g., a downlink shared channel (DL-SCH)transport block (TB)) and adopts a modulation scheme such as quadraturephase shift keying (QPSK), 16-ary quadrature amplitude modulation (16QAM), 64-ary QAM (64 QAM), or 256-ary QAM (256 QAM). A TB is encoded toa codeword. The PDSCH may deliver up to two codewords. The codewords areindividually subjected to scrambling and modulation mapping, andmodulation symbols from each codeword are mapped to one or more layers.An OFDM signal is generated by mapping each layer together with a DMRSto resources, and transmitted through a corresponding antenna port.

The PDCCH delivers DCI. For example, the PDCCH (i.e., DCI) may carryinformation about a transport format and resource allocation of a DLshared channel (DL-SCH), resource allocation information of an uplinkshared channel (UL-SCH), paging information on a paging channel (PCH),system information on the DL-SCH, information on resource allocation ofa higher-layer control message such as an RAR transmitted on a PDSCH, atransmit power control command, information about activation/release ofconfigured scheduling, and so on. The DCI includes a cyclic redundancycheck (CRC). The CRC is masked with various identifiers (IDs) (e.g. aradio network temporary identifier (RNTI)) according to an owner orusage of the PDCCH. For example, if the PDCCH is for a specific UE, theCRC is masked by a UE ID (e.g., cell-RNTI (C-RNTI)). If the PDCCH is fora paging message, the CRC is masked by a paging-RNTI (P-RNTI). If thePDCCH is for system information (e.g., a system information block(SIB)), the CRC is masked by a system information RNTI (SI-RNTI). Whenthe PDCCH is for an RAR, the CRC is masked by a random access-RNTI(RA-RNTI).

The PDCCH uses a fixed modulation scheme (e.g., QPSK). One PDCCHincludes 1, 2, 4, 8, or 16 control channel elements (CCEs) according toits aggregation level (AL). One CCE includes 6 resource element groups(REGs), each REG being defined by one OFDM symbol by one (P)RB.

The PDCCH is transmitted in a control resource set (CORESET). TheCORESET corresponds to a set of physical resources/parameters used todeliver the PDCCH/DCI in a BWP. For example, the CORESET is defined as aset of REGs with a given numerology (e.g., an SCS, a CP length, or thelike). The CORESET may be configured by system information (e.g., amaster information block (MIB)) or UE-specific higher-layer signaling(e.g., RRC signaling). For example, the following parameters/informationmay be used to configure a CORESET, and a plurality of CORESETs mayoverlap with each other in the time/frequency domain.

-   -   controlResourceSetId: indicates the ID of a CORESET.    -   frequencyDomainResources: indicates the frequency area resources        of the CORESET. The frequency area resources are indicated by a        bitmap, and each bit of the bitmap corresponds to an RB group        (i.e., six consecutive RBs). For example, the most significant        bit (MSB) of the bitmap corresponds to the first RB group of a        BWP. An RB group corresponding to a bit set to 1 is allocated as        frequency area resources of the CORESET.    -   duration: indicates the time area resources of the CORESET. It        indicates the number of consecutive OFDMA symbols in the        CORESET. For example, the duration is set to one of 1 to 3.    -   cce-REG-MappingType: indicates a CCE-to-REG mapping type. An        interleaved type and a non-interleaved type are supported.    -   precoderGranularity: indicates a precoder granularity in the        frequency domain.    -   tci-StatesPDCCH: provides information indicating a transmission        configuration indication (TCI) state for the PDCCH (e.g.,        TCI-StateID). The TCI state is used to provide the        quasi-co-location relation between DL RS(s) in an RS set        (TCI-state) and PDCCH DMRS ports.    -   tci-PresentInDCI: indicates whether a TCI field is included in        DCI.    -   pdcch-DMRS-ScramblingID: provides information used for        initialization of a PDCCH DMRS scrambling sequence.

To receive the PDCCH, the UE may monitor (e.g., blind-decode) a set ofPDCCH candidates in the CORESET. The PDCCH candidates are CCE(s) thatthe UE monitors for PDCCH reception/detection. The PDCCH monitoring maybe performed in one or more CORESETs in an active DL BWP on each activecell configured with PDCCH monitoring. A set of PDCCH candidatesmonitored by the UE is defined as a PDCCH search space (SS) set. The SSset may be a common search space (CSS) set or a UE-specific search space(USS) set.

Table 4 lists exemplary PDCCH SSs.

TABLE 4 Search Type Space RNTI Use Case Type0-PDCCH Common SI-RNTI on aprimary cell SIB Decoding Type0A-PDCCH Common SI-RNTI on a primary cellSIB Decoding Type1-PDCCH Common RA-RNTI or TC-RNTI on Msg2, Msg4 aprimary cell decoding in RACH Type2-PDCCH Common P-RNTI on a primarycell Paging Decoding Type3-PDCCH Common INT-RNTI, SFI-RNTI, TPC-PUSCH-RNTI, TPC-PUCCH- RNTI, TPC-SRS-RNTI, C- RNTI, MCS-C-RNTI, orCS-RNTI(s) UE Specific UE Specific C-RNTI, or MCS-C-RNTI, User specificor CS-RNTI(s) PDSCH decoding

The SS set may be configured by system information (e.g., MIB) orUE-specific higher-layer (e.g., RRC) signaling. S or fewer SS sets maybe configured in each DL BWP of a serving cell. For example, thefollowing parameters/information may be provided for each SS set. EachSS set may be associated with one CORESET, and each CORESETconfiguration may be associated with one or more SS sets.

-   -   searchSpaceId: indicates the ID of the SS set.    -   controlResourceSetId: indicates a CORESET associated with the SS        set.    -   monitoringSlotPeriodicityAndOffset: indicates a PDCCH monitoring        periodicity (in slots) and a PDCCH monitoring offset (in slots).    -   monitoringSymbolsWithinSlot: indicates the first OFDMA symbol(s)        for PDCCH monitoring in a slot configured with PDCCH monitoring.        The OFDMA symbols are indicated by a bitmap and each bit of the        bitmap corresponds to one OFDM symbol in the slot. The MSB of        the bitmap corresponds to the first OFDM symbol of the slot.        OFDMA symbol(s) corresponding to bit(s) set to 1 corresponds to        the first symbol(s) of the CORESET in the slot.    -   nrofCandidates: indicates the number of PDCCH candidates (e.g.,        one of 0, 1, 2, 3, 4, 5, 6, and 8) for each AL={1, 2, 4, 8, 16}.    -   searchSpaceType: indicates whether the SS type is CSS or USS.    -   DCI format: indicates the DCI format of PDCCH candidates

The UE may monitor PDCCH candidates in one or more SS sets in a slotbased on a CORESET/SS set configuration. An occasion (e.g.,time/frequency resources) in which the PDCCH candidates should bemonitored is defined as a PDCCH (monitoring) occasion. One or more PDCCH(monitoring) occasions may be configured in a slot.

Table 5 illustrates exemplary DCI formats transmitted on the PDCCH.

TABLE 5 DCI format Usage 0_0 Scheduling of PUSCH in one cell 0_1Scheduling of PUSCH in one cell 1_0 Scheduling of PDSCH in one cell 1_1Scheduling of PDSCH in one cell 2_0 Notifying a group of UEs of the slotformat 2_1 Notifying a group of UEs of the PRB(s) and OFDM symbol(s)where UE may assume no transmission is intended for the UE 2_2Transmission of TPC commands for PUCCH and PUSCH 2_3 Transmission of agroup of TPC commands for SRS transmissions by one or more UEs

DCI format 0_0 may be used to schedule a TB-based (or TB-level) PUSCH,and DCI format 0_1 may be used to schedule a TB-based (or TB-level)PUSCH or a code block group (CBG)-based (or CBG-level) PUSCH. DCI format1_0 may be used to schedule a TB-based (or TB-level) PDSCH, and DCIformat 1_1 may be used to schedule a TB-based (or TB-level) PDSCH or aCBG-based (or CBG-level) PDSCH (DL grant DCI). DCI format 0_0/0_1 may bereferred to as UL grant DCI or UL scheduling information, and DCI format1_0/1_1 may be referred to as DL grant DCI or DL scheduling information.DCI format 2_0 is used to deliver dynamic slot format information (e.g.,a dynamic slot format indicator (SFI)) to a UE, and DCI format 2_1 isused to deliver DL pre-emption information to a UE. DCI format 2_0and/or DCI format 2_1 may be delivered to a corresponding group of UEson a group common PDCCH which is a PDCCH directed to a group of UEs.

DCI format 0_0 and DCI format 1_0 may be referred to as fallback DCIformats, whereas DCI format 0_1 and DCI format 1_1 may be referred to asnon-fallback DCI formats. In the fallback DCI formats, a DCI size/fieldconfiguration is maintained to be the same irrespective of a UEconfiguration. In contrast, the DCI size/field configuration variesdepending on a UE configuration in the non-fallback DCI formats.

The PUCCH delivers uplink control information (UCI). The UCI includesthe following information.

-   -   SR: information used to request UL-SCH resources.    -   HARQ-ACK: a response to a DL data packet (e.g., codeword) on the        PDSCH. An HARQ-ACK indicates whether the DL data packet has been        successfully received. In response to a single codeword, a 1-bit        of HARQ-ACK may be transmitted. In response to two codewords, a        2-bit HARQ-ACK may be transmitted. The HARQ-ACK response        includes positive ACK (simply, ACK), negative ACK (NACK),        discontinuous transmission (DTX) or NACK/DTX. The term HARQ-ACK        is interchangeably used with HARQ ACK/NACK and ACK/NACK.    -   CSI: feedback information for a DL channel Multiple input        multiple output (MIMO)-related feedback information includes an        RI and a PMI.

Table 6 illustrates exemplary PUCCH formats. PUCCH formats may bedivided into short PUCCHs (Formats 0 and 2) and long PUCCHs (Formats 1,3, and 4) based on PUCCH transmission durations.

TABLE 6 Length in PUCCH OFDM symbols Number format N_(symb) ^(PUCCI) ofbits Usage Etc 0 1-2  ≤2 HARQ, SR Sequence selection 1 4-14 ≤2 HARQ,[SR] Sequence modulation 2 1-2  >2 HARQ, CSI, [SR] CP-OFDM 3 4-14 >2HARQ, CSI, [SR] DFT-s-OFDM (no UE multiplexing) 4 4-14 >2 HARQ, CSI,[SR] DFT-s-OFDM (Pre DFT OCC)

PUCCH format 0 conveys UCI of up to 2 bits and is mapped in asequence-based manner, for transmission. Specifically, the UE transmitsspecific UCI to the BS by transmitting one of a plurality of sequenceson a PUCCH of PUCCH format 0. Only when the UE transmits a positive SR,the UE transmits the PUCCH of PUCCH format 0 in PUCCH resources for acorresponding SR configuration.

PUCCH format 1 conveys UCI of up to 2 bits and modulation symbols of theUCI are spread with an orthogonal cover code (OCC) (which is configureddifferently whether frequency hopping is performed) in the time domain.The DMRS is transmitted in a symbol in which a modulation symbol is nottransmitted (i.e., transmitted in time division multiplexing (TDM)).

PUCCH format 2 conveys UCI of more than 2 bits and modulation symbols ofthe DCI are transmitted in frequency division multiplexing (FDM) withthe DMRS. The DMRS is located in symbols #1, #4, #7, and #10 of a givenRB with a density of 1/3. A pseudo noise (PN) sequence is used for aDMRS sequence. For 2-symbol PUCCH format 2, frequency hopping may beactivated.

PUCCH format 3 does not support UE multiplexing in the same PRBS, andconveys UCI of more than 2 bits. In other words, PUCCH resources ofPUCCH format 3 do not include an OCC. Modulation symbols are transmittedin TDM with the DMRS.

PUCCH format 4 supports multiplexing of up to 4 UEs in the same PRBS,and conveys UCI of more than 2 bits. In other words, PUCCH resources ofPUCCH format 3 include an OCC. Modulation symbols are transmitted in TDMwith the DMRS.

The PUSCH delivers UL data (e.g., UL-shared channel transport block(UL-SCH TB)) and/or UCI based on a CP-OFDM waveform or a DFT-s-OFDMwaveform. When the PUSCH is transmitted in the DFT-s-OFDM waveform, theUE transmits the PUSCH by transform precoding. For example, whentransform precoding is impossible (e.g., disabled), the UE may transmitthe PUSCH in the CP-OFDM waveform, while when transform precoding ispossible (e.g., enabled), the UE may transmit the PUSCH in the CP-OFDMor DFT-s-OFDM waveform. A PUSCH transmission may be dynamicallyscheduled by a UL grant in DCI, or semi-statically scheduled byhigher-layer (e.g., RRC) signaling (and/or Layer 1 (L1) signaling suchas a PDCCH) (configured scheduling or configured grant). The PUSCHtransmission may be performed in a codebook-based or non-codebook-basedmanner.

On DL, the BS may dynamically allocate resources for DL transmission tothe UE by PDCCH(s) (including DCI format 1_0 or DCI format 1_1).Further, the BS may indicate to a specific UE that some of resourcespre-scheduled for the UE have been pre-empted for signal transmission toanother UE, by PDCCH(s) (including DCI format 2_1). Further, the BS mayconfigure a DL assignment periodicity by higher-layer signaling andsignal activation/deactivation of a configured DL assignment by a PDCCHin a semi-persistent scheduling (SPS) scheme, to provide a DL assignmentfor an initial HARQ transmission to the UE. When a retransmission forthe initial HARQ transmission is required, the BS explicitly schedulesretransmission resources through a PDCCH. When a DCI-based DL assignmentcollides with an SPS-based DL assignment, the UE may give priority tothe DCI-based DL assignment.

Similarly to DL, for UL, the BS may dynamically allocate resources forUL transmission to the UE by PDCCH(s) (including DCI format 0_0 or DCIformat 0_1). Further, the BS may allocate UL resources for initial HARQtransmission to the UE based on a configured grant (CG) method(similarly to SPS). Although dynamic scheduling involves a PDCCH for aPUSCH transmission, a configured grant does not involve a PDCCH for aPUSCH transmission. However, UL resources for retransmission areexplicitly allocated by PDCCH(s). As such, an operation ofpreconfiguring UL resources without a dynamic grant (DG) (e.g., a ULgrant through scheduling DCI) by the BS is referred to as a “CG”. Twotypes are defined for the CG.

-   -   Type 1: a UL grant with a predetermined periodicity is provided        by higher-layer signaling (without L1 signaling).    -   Type 2: the periodicity of a UL grant is configured by        higher-layer signaling, and activation/deactivation of the CG is        signaled by a PDCCH, to provide the UL grant.

FIG. 5 illustrates exemplary UL transmission operations of a UE. The UEmay transmit an intended packet based on a DG (FIG. 5(a)) or based on aCG (FIG. 5(b)).

Resources for CGs may be shared between a plurality of UEs. A UL signaltransmission based on a CG from each UE may be identified bytime/frequency resources and an RS parameter (e.g., a different cyclicshift or the like). Therefore, when a UE fails in transmitting a ULsignal due to signal collision, the BS may identify the UE andexplicitly transmit a retransmission grant for a corresponding TB to theUE.

K repeated transmissions including an initial transmission are supportedfor the same TB by a CG. The same HARQ process ID is determined for Ktimes repeated UL signals based on resources for the initialtransmission. The redundancy versions (RVs) of a K times repeated TBhave one of the patterns {0, 2, 3, 1}, {0, 3, 0, 3}, and {0, 0, 0, 0}.

FIG. 6 illustrates exemplary repeated transmissions based on a CG.

The UE performs repeated transmissions until one of the followingconditions is satisfied:

-   -   A UL grant for the same TB is successfully received;    -   The repetition number of the TB reaches K; and    -   (In Option 2) the ending time of a period P is reached.

Similarly to licensed-assisted access (LAA) in the legacy 3GPP LTEsystem, use of an unlicensed band for cellular communication is alsounder consideration in a 3GPP NR system. Unlike LAA, a stand-along (SA)operation is aimed in an NR cell of an unlicensed band (hereinafter,referred to as NR unlicensed cell (UCell)). For example, PUCCH, PUSCH,and PRACH transmissions may be supported in the NR UCell.

In an NR system to which various embodiments of the present disclosureare applicable, up to 400 MHz per component carrier (CC) may beallocated/supported. When a UE operating in such a wideband CC alwaysoperates with a radio frequency (RF) module turned on for the entire CC,battery consumption of the UE may increase.

Alternatively, considering various use cases (e.g., eMBB, URLLC, mMTC,and so on) operating within a single wideband CC, a different numerology(e.g., SCS) may be supported for each frequency band within the CC.

Alternatively, each UE may have a different maximum bandwidthcapability.

In this regard, the BS may indicate to the UE to operate only in apartial bandwidth instead of the total bandwidth of the wideband CC. Thepartial bandwidth may be defined as a bandwidth part (BWP).

A BWP may be a subset of contiguous RBs on the frequency axis. One BWPmay correspond to one numerology (e.g., SCS, CP length, slot/mini-slotduration, and so on).

The BS may configure multiple BWPs in one CC configured for the UE. Forexample, the BS may configure a BWP occupying a relatively smallfrequency area in a PDCCH monitoring slot, and schedule a PDSCHindicated (or scheduled) by a PDCCH in a larger BWP. Alternatively, whenUEs are concentrated on a specific BWP, the BS may configure another BWPfor some of the UEs, for load balancing. Alternatively, the BS mayexclude some spectrum of the total bandwidth and configure both-sideBWPs of the cell in the same slot in consideration of frequency-domaininter-cell interference cancellation between neighboring cells.

The BS may configure at least one DL/UL BWP for a UE associated with thewideband CC, activate at least one of DL/UL BWP(s) configured at aspecific time point (by L1 signaling (e.g., DCI), MAC signaling, or RRCsignaling), and indicate switching to another configured DL/UL BWP (byL1 signaling, MAC signaling, or RRC signaling). Further, upon expirationof a timer value (e.g., a BWP inactivity timer value), the UE may switchto a predetermined DL/UL BWP. The activated DL/UL BWP may be referred toas an active DL/UL BWP. During initial access or before an RRCconnection setup, the UE may not receive a configuration for a DL/UL BWPfrom the BS. A DL/UL BWP that the UE assumes in this situation isdefined as an initial active DL/UL BWP.

Embodiments of the Present Disclosure

FIG. 7 illustrates an exemplary wireless communication system supportingan unlicensed band applicable to the present disclosure.

In the following description, a cell operating in a licensed band(L-band) is defined as an L-cell, and a carrier of the L-cell is definedas a (DL/UL) LCC. A cell operating in an unlicensed band (U-band) isdefined as a U-cell, and a carrier of the U-cell is defined as a (DL/UL)UCC. The carrier/carrier-frequency of a cell may refer to the operatingfrequency (e.g., center frequency) of the cell. A cell/carrier (e.g.,CC) is commonly called a cell.

When a BS and a UE transmit and receive signals on carrier-aggregatedLCC and UCC as illustrated in FIG. 7(a), the LCC and the UCC may beconfigured as a primary CC (PCC) and a secondary CC (SCC), respectively.The BS and the UE may transmit and receive signals on one UCC or on aplurality of carrier-aggregated UCCs as illustrated in FIG. 7(b). Inother words, the BS and UE may transmit and receive signals only onUCC(s) without using any LCC. For an SA operation, PRACH, PUCCH, PUSCH,and SRS transmissions may be supported on a UCell.

Signal transmission and reception operations in an unlicensed band asdescribed in the present disclosure may be applied to theafore-mentioned deployment scenarios (unless specified otherwise).

Unless otherwise noted, the definitions below are applicable to thefollowing terminologies used in the present disclosure.

-   -   Channel: a carrier or a part of a carrier composed of a        contiguous set of RBs in which a channel ccess procedure (CAP)        is performed in a shared spectrum.    -   Channel access procedure (CAP): a procedure of assessing channel        availability based on sensing before signal transmission in        order to determine whether other communication node(s) are using        a channel. A basic sensing unit is a sensing slot with a        duration of T_(sl)=9 us. The BS or the UE senses the slot during        a sensing slot duration. When power detected for at least 4 us        within the sensing slot duration is less than an energy        detection threshold X_(thresh), the sensing slot duration T_(sl)        is be considered to be idle. Otherwise, the sensing slot        duration T_(sl) is considered to be busy. CAP may also be called        listen before talk (LBT),    -   Channel occupancy: transmission(s) on channel(s) from the BS/UE        after a CAP.    -   Channel occupancy time (COT): a total time during which the        BS/UE and any BS/UE(s) sharing channel occupancy performs        transmission(s) on a channel after a CAP. Regarding COT        determination, if a transmission gap is less than or equal to 25        us, the gap duration may be counted. in a COT. The COT may be        shared for transmission between the BS and corresponding UE(s).    -   DL transmission burst: a set of transmissions without any gap        greater than 16 us from the BS. Transmissions from the BS, which        are separated by a gap exceeding 16 us are considered as        separate DL transmission bursts. The BS may perform        transmission(s) after a gap without sensing channel availability        within a DL transmission burst.    -   UL transmission burst: a set of transmissions without any gap        greater than 16 us from the UE. Transmissions from the UE, which        are separated by a gap exceeding 16 us are considered. as        separate UL transmission bursts. The UE may perform        transmission(s) after a gap without sensing channel availability        within a DL transmission burst.    -   Discovery burst: a DL transmission burst including a set of        signal(s) and/or channel(s) confined within a window and        associated with a duty cycle. The discovery burst may include        transmission(s) initiated by the BS, which includes a PSS, an        SSS, and a cell-specific RS (CRS) and further includes a        non-zero power CSI-RS. In the NR system, the discover burst        includes may include transmission(s) initiated by the BS, which        includes at least an SS/PBCH block and further includes a        CORESET for a PDCCH scheduling a PDSCH carrying SIB 1 the PDSCH        carrying SIB 1, and/or a non-zero power CSI-RS.

FIG. 8 illustrates an exemplary method of occupying resources in anunlicensed band.

Referring to FIG. 8, a communication node (e.g., a BS or a UE) operatingin an unlicensed band should determine whether other communicationnode(s) is using a channel, before signal transmission. For thispurpose, the communication node may perform a CAP to access channel(s)on which transmission(s) is to be performed in the unlicensed band. TheCAP may be performed based on sensing. For example, the communicationnode may determine whether other communication node(s) is transmitting asignal on the channel(s) by carrier sensing (CS) before signaltransmission. Determining that other communication node(s) is nottransmitting a signal is defined as confirmation of clear channelassessment (CCA). In the presence of a CCA threshold (e.g., X_(thresh))which has been predefined or configured by higher-layer (e.g., RRC)signaling, the communication node may determine that the channel isbusy, when detecting energy higher than the CCA threshold in thechannel. Otherwise, the communication node may determine that thechannel is idle. When determining that the channel is idle, thecommunication node may start to transmit a signal in the unlicensedband. CAP may be replaced with LBT.

Table 7 describes an exemplary CAP supported in NR-U.

TABLE 7 Type Explanation DL Type 1 CAP CAP with random backoff timeduration spanned by the sensing slots that are sensed to be idle beforea downlink transmission(s) is random Type 2 CAP CAP without randombackoff Type 2A, 2B, 2C time duration spanned by sensing slots that aresensed to be idle before a downlink transmission(s) is deterministic ULType 1 CAP CAP with random backoff time duration spanned by the sensingslots that are sensed to be idle before a downlink transmission(s) israndom Type 2 CAP CAP without random backoff Type 2A, 2B, 2C timeduration spanned by sensing slots that are sensed to be idle before adownlink transmission(s) is deterministic

In a wireless communication system supporting an unlicensed band, onecell (or carrier (e.g., CC)) or BWP configured for a UE may be awideband having a larger bandwidth (BW) than in legacy LTE. However, aBW requiring CCA based on an independent LBT operation may be limitedaccording to regulations. Let a subband (SB) in which LBT isindividually performed be defined as an LBT-SB. Then, a plurality ofLBT-SBs may be included in one wideband cell/BWP. A set of RBs includedin an LBT-SB may be configured by higher-layer (e.g., RRC) signaling.Accordingly, one or more LBT-SBs may be included in one cell/BWP basedon (i) the BW of the cell/BWP and (ii) RB set allocation information.

A plurality of LBT-SBs may be included in the BWP of a cell (orcarrier). An LBT-SB may be, for example, a 20-MHz band. The LBT-SB mayinclude a plurality of contiguous (P)RBs in the frequency domain, andthus may be referred to as a (P)RB set.

A UE performs a Type 1 or Type 2 CAP for a UL signal transmission in anunlicensed band. In general, the UE may perform a CAP (e.g., Type 1 orType 2) configured by a BS, for a UL signal transmission. For example,CAP type indication information may be included in a UL grant (e.g., DCIformat 0_0 or DCI format 0_1) that schedules a PUSCH transmission.

In the Type 1 UL CAP, the length of a time period spanned by sensingslots sensed as idle before transmission(s) is random. The Type 1 UL CAPmay be applied to the following transmissions.

-   -   PUSCH/SRS transmission(s) scheduled and/or configured by BS    -   PUCCH transmission(s) scheduled and/or configured by BS    -   Transmission(s) related to random access procedure (RAP)

FIG. 9 illustrates a Type 1 CAP among CAPs of a UE for a UL signaltransmission in an unlicensed band applicable to the present disclosure.

Referring to FIG. 9, the UE may sense whether a channel is idle for asensing slot duration in a defer duration T_(d). After a counter N isdecremented to 0, the UE may perform a transmission (S934). The counterN is adjusted by sensing the channel for additional slot duration(s)according to the following procedure.

Step 1) Set N=N_(init) where N_(init) is a random number uniformlydistributed between 0 and CW_(p), and go to step 4 (S920).

Step 2) If N>0 and the UE chooses to decrement the counter, set N=N−1(S940).

Step 3) Sense the channel for an additional slot duration, and if theadditional slot duration is idle (Y), go to step 4. Else (N), go to step5 (S950).

Step 4) If N=0 (Y) (S930), stop CAP (S932). Else (N), go to step 2.

Step 5) Sense the channel until a busy sensing slot is detected withinthe additional defer duration T_(d) or all slots of the additional deferduration T_(d) are sensed as idle (S960).

Step 6) If the channel is sensed as idle for all slot durations of theadditional defer duration T_(d) (Y), go to step 4. Else (N), go to step5 (S970).

Table 8 illustrates that m_(p), a minimum CW, a maximum CW, a maximumchannel occupancy time (MCOT), and an allowed CW size applied to a CAPvary according to channel access priority classes.

TABLE 8 Channel Access Priority allowed Class (p) m_(p) CW_(min, p)CW_(max, p) T_(ulmcot, p) CW_(p) sizes 1 2 3 7 2 ms {3, 7} 2 2 7 15 4 ms{7, 15} 3 3 15 1023 6 or 10 ms {15, 31, 63, 127, 255, 511, 1023} 4 7 151023 6 or 10 ms {15, 31, 63, 127, 255, 511, 1023}

The defer duration T_(d) includes a duration T_(f) (16 us) immediatelyfollowed by m_(p) consecutive slot durations where each slot durationT_(sl) is 9 us, and T_(f) includes a sensing slot duration T_(sl) at thestart of the 16-us duration.

CW_(Wmin,p)<=CW_(p)<=CW_(max,p). CW_(p) is set to CW_(min,p), and may beupdated before Step 1 based on an explicit/implicit reception responseto a previous UL burst (e.g., PUSCH) (CW size update). For example,CW_(p) may be initialized to CW_(min,p) based on an explicit/implicitreception response to the previous UL burst, may be increased to thenext higher allowed value, or may be maintained to be an existing value.

In the Type 2 UL CAP, the length of a time period spanned by sensingslots sensed as idle before transmission(s) is deterministic. Type 2 ULCAPs are classified into Type 2A UL CAP, Type 2B UL CAP, and Type 2C ULCAP. In the Type 2A UL CAP, the UE may transmit a signal immediatelyafter the channel is sensed as idle during at least a sensing durationT_(short_dl) (=25 us). T_(short_dl) includes a duration Tf (=16 us) andone immediately following sensing slot duration. In the Type 2A UL CAP,T_(f) includes a sensing slot at the start of the duration. In the Type2B UL CAP, the UE may transmit a signal immediately after the channel issensed as idle during a sensing slot duration T_(f) (=16 us). In theType 2B UL CAP, T_(f) includes a sensing slot within the last 9 us ofthe duration. In the Type 2C UL CAP, the UE does not sense a channelbefore a transmission.

To allow the UE to transmit UL data in the unlicensed band, the BSshould succeed in an LBT operation to transmit a UL grant in theunlicensed band, and the UE should also succeed in an LBT operation totransmit the UL data. That is, only when both of the BS and the UEsucceed in their LBT operations, the UE may attempt the UL datatransmission. Further, because a delay of at least 4 msec is involvedbetween a UL grant and scheduled UL data in the LTE system, earlieraccess from another transmission node coexisting in the unlicensed bandduring the time period may defer the scheduled UL data transmission ofthe UE. In this context, a method of increasing the efficiency of ULdata transmission in an unlicensed band is under discussion.

To support a UL transmission having a relatively high reliability and arelatively low time delay, NR also supports CG type 1 and CG type 2 inwhich the BS preconfigures time, frequency, and code resources for theUE by higher-layer signaling (e.g., RRC signaling) or both ofhigher-layer signaling and L1 signaling (e.g., DCI). Without receiving aUL grant from the BS, the UE may perform a UL transmission in resourcesconfigured with type 1 or type 2. In type 1, the periodicity of a CG, anoffset from SFN=0, time/frequency resource allocation, a repetitionnumber, a DMRS parameter, an MCS/TB size (TBS), a power controlparameter, and so on are all configured only by higher-layer signalingsuch as RRC signaling, without L1 signaling. Type 2 is a scheme ofconfiguring the periodicity of a CG and a power control parameter byhigher-layer signaling such as RRC signaling and indicating informationabout the remaining resources (e.g., the offset of an initialtransmission timing, time/frequency resource allocation, a DMRSparameter, and an MCS/TBS) by activation DCI as L1 signaling.

Before a description of proposed methods, NR-based channel accessschemes for an unlicensed band used in the present disclosure areclassified as follows.

-   -   Category 1 (Cat-1): the next transmission immediately follows        the previous transmission after a switching gap within a COT,        and the switching gap is shorter than 16 us, including even a        transceiver turn-around time. Cat-1 LBT may correspond to the        above-described Type 2C CAP.    -   Category 2 (Cat-2): an LBT method without backoff. Once a        channel is confirmed to be idle during a specific time period        shortly before transmission, the transmission may be performed        immediately. Cat-2 LBT may be subdivided according to the length        of a minimum sensing duration required for channel sensing        immediately before a transmission. For example, Cat-2 LBT with a        minimum sensing duration of 25 us may correspond to the        above-described Type 2A CAP, and Cat-2 LBT with a minimum        sensing duration of 16 us may correspond to the above-described        Type 2B CAP. The minimum sensing durations are merely exemplary,        and a minimum sensing duration less than 25 us or 16 us (e.g., a        minimum sensing duration of 9 us) may also be available.    -   Category 3 (Cat-3): an LBT method with fixed contention window        size (CWS)i-based backoff. A transmitting entity selects a        random number N in a range of 0 to a (fixed) maximum CWS value        and decrements a counter value each time it determines that a        channel is idle. When the counter value reaches 0, the        transmitting entity is allowed to perform a transmission.    -   Category 4 (Cat-4): an LBT method with variable CWS-based        backoff. A transmitting entity selects a random number N in a        range of 0 to a (variable) maximum CWS value and decrements a        counter value, each time it determines that a channel is idle.        When the counter value reaches 0, the transmitting entity is        allowed to perform a transmission. If the transmitting entity        receives a feedback indicating reception failure of the        transmission, the transmitting entity increases the maximum CWS        value by one level, selects a random number again within the        increased CWS value, and performs an LBT procedure. Cat-4 LBT        may correspond to the above-described Type 1 CAP.

The following description is given with the appreciation that the termband may be interchangeably used with CC/cell, and a CC/cell (index) maybe replaced with a BWP (index) configured within the CC/cell, or acombination of the CC/cell (index) and the BWP (index).

Terms are defined as follows.

-   -   UCI: control information transmitted on UL by the UE. UCI        includes various types of control information (i.e., UCI types).        For example, the UCI may include an HARQ-ACK (simply, A/N or        AN), an SR, and CSI.    -   PUCCH: a physical layer UL channel for UCI transmission. For        convenience, PUCCH resources configured and/or indicated for        A/N, SR, and CSI transmission are referred to as A/N PUCCH        resources, SR PUCCH resources, and CSI PUCCH resources,        respectively.    -   UL grant DCI: DCI for a UL grant. For example, UL grant DCI        means DCI formats 0_0 and 0_1, and is transmitted on a PDCCH.    -   DL assignment/grant DCI: DCI for a DL grant. For example, DL        assignment/grant DCI means DCI formats 1_0 and 1_1, and is        transmitted on a PDCCH.    -   PUSCH: a physical layer UL channel for UL data transmission.    -   Slot: a basic time unit (TU) (or time interval) for data        scheduling. A slot includes a plurality of symbols. Herein, a        symbol includes an OFDM symbol (e.g., CP-OFDM symbol or        DFT-s-OFDM symbol). In this specification, the terms symbol,        OFDM-based symbol, OFDM symbol, CP-OFDM symbol, and DFT-s-OFDM        symbol may be replaced with each other.    -   Channel: a carrier or a part of a carrier composed of a set of        contiguous RBs in which a CAP is performed in a shared spectrum.        For example, a channel may mean a frequency unit in which LBT is        performed, and may be interchangeably used with an LBT-SB in the        following description.    -   LBT for channel X: this means that LBT is performed to check        whether channel X is available. For example, before a        transmission starts on channel X, a CAP may be performed.

Frame based equipment (FBE) is equipment that transmits and receivessignals at a periodic timing with a periodicity equal to a fixed frameperiod (FFP). To allow the FBE to perform channel access on an operatingchannel in an unlicensed band, an LBT-based channel access mechanismshould be implemented. LBT refers to a CCA mechanism performed beforechannel access and is performed in a single observation slot. Anobservation slot is a time period during which it is determined whetherthere is any transmission from another radio local area network (RLAN)on an operating channel, which is at least 9 us. A device that initiatesone or more transmissions is referred to as an initiating device.Otherwise, the device is referred to as a responding device. The FBE maybe an initiating device, a responding device, or both.

FIG. 9 illustrates an exemplary timing structure for the FBE, in whichan FFP including a COT of a predetermined duration and an idle period isperiodically repeated. CCA is performed in an observation slot withinthe idle period. When there is no other RLAN transmission on anoperating channel as a result of CCA in the observation slot within theidle period of FFP #N, that is, the energy measurement of theobservation slot is less than a CCA threshold, the UE may start atransmission in the COT of FFP #N+1. Supported FFP values are announcedby a device manufacturer and range from lms to 10 ms. A device maychange an FFP only once per 200 ms. The length of the COT in the FFP maynot exceed 95% of the length of the FFP, and the idle period should beset to at least 5% of the COT length, at least 100 us.

In FBE mode, Cat-1 LBT and Cat-2 LBT may be used the BS and the UE. Thatis, the BS or the UE operating in the FBE mode may use a CAP that is notbased on random backoff. Cat-2 LBT may be performed 25 us just beforethe start of the next FFP in the idle period within the previous 1-1-P,or may be applied when the gap between transmissions such as a DL-to-DL,UL-to-DL, DL-to-UL, or UL-to-DL gap, is 25 us or 16 us. Alternatively,when the gap between transmissions exceeds 16 us, Cat-2 LBT may beapplied. Cat-1 LBT may be applied when the gap between transmissions is16 us or when the gap between transmissions is up to 16 us. Thetransmission duration of a signal/channel transmitted after Cat-1 LBTmay be limited.

The present disclosure proposes a method of transmitting andconfiguring/indicating a signal/channel such as a PRACH, a configuredgrant (CG) PUSCH, a periodic/semi-persistent PUCCH, and aperiodic/semi-persistent SRS, when a BS and a UE operate in the FBE mode(when a BS and a UE operate in a transmission/reception structure havinga periodic timing with a periodicity equal to an FFP).

To initially access the BS, the UE receives cell-related information andRACH configuration information in a PBCH and remaining minimum systeminformation (RMSI) broadcast by the BS. RMSI is system informationacquired based on a master information block (MIB) acquired from thePBCH, and may be referred to as system information block 1 (SIB1). TheBS broadcasts the PBCH and RMSI including the cell-related informationand the RACH configuration information, for UEs initially accessing theBS. The UE transmits an RACH preamble (PRACH) at a time/frequencyconfigured by the RACH configuration information in the RMSI. The RMSIreceived from the BS may explicitly indicate/configure the FBE modeto/for the UE, along with information such as an FFP and an idle period,or the RACH configuration may indicate/configure Cat-2 (or Cat-1) as theLBT type to/for the UE so that the UE may implicitly determine the FBEmode. Alternatively, the RACH configuration may indicate/configure Cat-4as the LBT type to/for the UE so that the UE may implicitly determinethe operation mode to be load based equipment (LBE) mode. According tothe indicated/configured LBT type, the UE may identify the operationmode as the LBE mode or the FBE mode.

However, the LBT types are exemplary. The UE may determine whether theoperation mode is the LBE mode or the FBE mode according to whether theindicated LBT type is or is not based on random backoff.

The FBE mode and the LBE mode may be types of channel access mode.

That is, both the FBE mode and the LBE mode may be supported as channelaccess modes in a wireless communication system supporting an unlicensedband to which the present disclosure is applied.

The LBE mode may refer to a mode in which when a UE or a BS is totransmit a signal, the UE or the BS transmits the signal based on theresult of a CAP. Compared to the FBE mode in which a signal may betransmitted by performing a CAP only in an FFP, the UE or the BS maytransmit a signal by performing a CAP irrespective of a specificperiodicity such as the FFP in the LBE mode. In the above description,Cat-4 is exemplary, and the UE or the BS may perform both a randombackoff-based CAP and a non-random backoff-based CAP in the LBE mode.For example, when the UE operates in the LBE mode, the UE may performany of a Type 1 CAP, a Type 2A CAP, a Type 2B CAP, and a Type 2C CAP.

In contrast, the UE or the BS may perform only a non-randombackoff-based CAP, that is, a CAP corresponding to Cat-1 or Cat-2 in theFBE mode. In the FBE mode, once a channel is confirmed as idle, forexample, for 9 us, a signal transmission may be allowed. Referring toFIG. 10, the UE or the BS may perform a CAP only in the idle period ofan FFP, and the CAP may not be based on random backoff.

As the wireless communication system supporting an unlicensed band towhich the present disclosure is applied supports two types of channelaccess modes, the UE needs to know the channel access mode of a servingcell or a cell to be accessed.

As described above, the UE may acquire a channel access mode through ahigher-layer signal (e.g., SIB). In the case of the FBE mode, the UE mayalso acquire FFP-related information from the higher-layer signal.

Before a description of proposed method #1, an overall PRACHtransmission operation of a UE will be described. The UE receivesinformation about an RACH configuration, and acquires information aboutthe starting OFDM symbol of a PRACH transmission, an RACH slot, and thenumber of a plurality of RACH occasions (ROs) included in the RACH slotbased on the RACH configuration. The UE may transmit a PRACH in aspecific RO among the plurality of ROs based on the acquiredinformation. An RO in which a PRACH is transmitted is referred to as a“valid RO”.

Each of the proposed methods described below may be applied incombination with other proposed methods, unless they contradict witheach other.

[Proposed method #1] When the FBE mode is indicated/configured to/forthe UE or the LBT type of a PRACH is indicated/configured as Cat-2 (orCat-1), by RMSI and/or another SIB and/or a UE-dedicated RRC signalreceived from the BS, the UE may transmit the PRACH in a “valid RO”within x ms (or x slots) upon receipt/detection of a specificsignal/channel. For example, the UE may transmit the PRACH in a validRO, considering an RO within a predetermined time after receiving thespecific signal to be valid. The starting time of x may be defined(relatively) from the start or end of the specific signal/channel (orCORESET) or as an absolute time (e.g., every frame boundary or thestarting time of every DRS transmission window). The specificsignal/channel of which the reception/detection triggers transmission ofthe PRACH may be configured by RMSI or determined according to adefinition in the standards. The signal/channel based on which whetherthe UE is to transmit the PRACH is determined may be configured on an RObasis or for an RO group (or for all ROs). Further, the value of x maybe predefined or signaled by RMSI and/or another SIB and/or aUE-dedicated RRC signal.

When the UE fails in receiving/detecting the specific signal/channel,the UE may not attempt to transmit the PRACH (or perform LBT for thePRACH) in an RO associated with the specific signal/channel, consideringthat the BS has failed in LBT. In the case where an FFP is configured,when the UE succeeds in LBT, the UE may attempt to transmit the PRACH inan RO configured at an FFP boundary among ROs configured in an RACHslot, irrespective of reception/detection of the specificsignal/channel.

The BS may define two Cat-2 LBT types that the UE is supposed to performbefore the PRACH transmission and signal one of the two Cat-2 BLT typesto the UE. For example, for Cat-2 LBT Type 1, the UE may consider that aconfigured specific RO is always valid under any condition, and transmitthe PRACH, upon acquisition of a UE-initiated COT by Cat-2 LBT in thespecific RO. That is, the UE may perform a CAP and transmit the PRACH inthe specific RO, serving as an initiating device, irrespective ofwhether the UE has detected the specific signal. In another example, forCat-2 LBT Type 2, the UE may determine the validity of an RO accordingto whether the specific signal/channel has been received/detected andtransmit the PRACH by sharing a COT of the BS, when succeeding in Cat-2LBT. That is, after determining whether an RO is valid depending onwhether a gNB-initiated COT has been detected, the UE may transmit thePRACH by sharing the COT of the BS, when succeeding in Cat-2 LBT in avalid RO. Alternatively, with a plurality of ROs configured, a Cat-2 LBTtype to be used may be configured/indicated on a configured RO basis byan RRC signal or RMSI, or whether an RO is configured in the middle ofan FFP or in alignment with the starting time of the FFP may beconfigured/indicated on an RO basis.

Before transmitting the PRACH, the UE should attempt to receive/detectall or some of the following signals/channels.

(1) PSS and/or SSS (of serving cell)

(2) PBCH DMRS and/or PBCH payload (of serving cell)

(3) RMSI PDCCH and/or PDSCH (of serving cell)

(4) PDCCH scrambled with specific RNTI (e.g., P-RNTI, SI-RNTI, or thelike) (of serving cell)

PDCCH and/or PDSCH reception may include DMRS detection. Further, everychannel/signal may be linked to an RO selected by the UE. For example,in the case where the UE intends to select an RO linked to a specificSSB index (or SSB beam index) and transmit a specific PRACH preamble inthe RO resources, when the UE succeeds in detecting/decoding a PSSand/or an SSS and/or a PBCH DMRS and/or PBCH payload and/or an RMSIPDCCH and/or an RMSI PDSCH and/or paging DCI and/or a paging message,which is placed in a quasi co-location (QCL) relationship with the SSBindex (or SSB beam index), the UE may transmit the PRACH in a “valid RO”within x ms (or x slots). When a signal/channel of which thedetection/reception triggers a PRACH transmission has not been defined,the UE may attempt to transmit the PRACH in a corresponding RO (in thesame manner as in the operation in an RO aligned with an FFP boundary),when succeeding in LBT. Further, when an LBT type is indicated as Cat-2or Cat-1 by RMSI or a PDCCH or when it is predefined that Cat-1 is usedfor a specific signal/channel, an RO with a limited time length may beconfigured or defined.

This proposed method is also applicable for msgA PUSCH transmission in a2-step RACH procedure. Specifically, the 2-step RACH procedure may be aprocedure in which after transmitting an msgA PRACH preamble in an RO, aUE transmits an msgA PUSCH without a feedback (e.g., msg2 such as arandom access response (RAR) in a 4-step RACH procedure) from acorresponding BS, and the BS receiving the msgA PUSCH transmits msgBcorresponding to msgA, thereby achieving contention resolution only intwo steps. msgA PUSCH transmission resources may be defined as a PUSCHoccasion (PO). When a gap is configured between an RO and a PO, LBT maybe supposed to be performed immediately before the PO and the proposedmethod may be applied in relation to an LBT method.

For an msgA PRACH preamble configured with the FBE mode, for example,when the UE attempts to transmit the msgA PRACH preamble aftersucceeding in Cat-2 (or Cat-1) LBT in a specific RO, the UE may beallowed to transmit an msgA PUSCH in a PO associated with the ROirrespective of reception/detection of a DL signal/channel, upon successof Cat-2 (or Cat-1) LBT. Alternatively, a different rule may be definedaccording to a timing gap (predefined or configured) between an RO and aPO. For example, when the timing gap spans Y or fewer slots (ormilliseconds), the UE may be allowed to transmit the msgA PUSCH in thePO associated with the transmission RO irrespective ofreception/detection of the DL signal/channel, upon success of Cat-2 (orCat-1) LBT. When the timing gap spans more slots (or milliseconds) thanY, the UE may be allowed to transmit the msgA PUSCH in the PO associatedwith the transmission RO according to reception/detection of the DLsignal/channel, upon success of Cat-2 (or Cat-1) LBT.

The BS may transmit information required for initial access to a cell tothe UE by a PBCH and RMSI which are broadcast. The BS may explicitlytransmit information about an FFP and an idle period for the FBE mode orimplicitly indicate the FBE mode by configuring/indicating an LBT typefor PRACH transmission as Cat-2 for/to the UE. The UE may receiveinformation required for RACH transmission by receiving an RACHconfiguration in the RMSI. The RACH configuration may includeinformation about time/frequency resources and an LBT type, for an RACHprocedure.

The UE may transmit the PRACH (in FFP #N+1) after succeeding in Cat-2LBT in the idle period of the previous FFP (FFP #N) or after performingCat-2 (or Cat-1) LBT by sharing a COT which the BS has obtained by LBTsuccess. An RO configuration in an RACH slot and a signal/channel ofwhich the reception/detection triggers PRACH transmission may be definedin RMSI or standards. When the UE fails in detecting the specificsignal/channel (in FFP #N), the UE may not transmit the PRACH in ROs ofa corresponding FFP (FFP #N), considering that the BS has failed in theLBT and thus has not acquired the COT (of FFP #N). Alternatively, whenthe UE acquires a COT by Cat-2 LBT in a specific RO configured inalignment with an FFP boundary among ROs configured in the RACH slot,the UE may transmit the RACH according to a configuration. Further, whenCat-1 LBT is indicated/configured to/for the UE, the UE may be allowedto transmit the RACH only in a specific RO configured to have a limitedtime length.

When the UE detects the specific signal/channel, the UE may transmit thePRACH in a valid RO within x ms (or x slots), and the starting time of xmay be defined as the start or end of the following signal/channel (orCORESET) or as an absolute time. PDCCH reception may include DMRSdetection and the specific channel/signal may be linked to an ROselected by the UE. For example, when the UE succeeds in receiving anRMSI PDCCH, the UE may perform Cat-2 LBT in one of valid ROs within thepreconfigured x ms. When a measured energy is lower than a threshold,the UE may determine the channel to be idle and transmit the PRACH usingfrequency resources and a sequence based on the RACH configuration.

[Proposed method #2] The FBE mode may be indicated/configured to/for theUE or the LBT type of a configured grant (CG)-PUSCH (or aperiodic/semi-persistent SRS or a periodic/semi-persistent PUCCH) may beindicated/configured as Cat-2 (or Cat-1) LBT to/for the UE, by RMSIand/or another SIB and/or a UE-dedicated RRC signal received from theBS. When the UE succeeds in receiving/detecting a specific PDCCH, the UEis allowed to transmit a CG-PUSCH within x ms (or x slots). In otherwords, when the UE succeeds in the LBT of the configured/indicated LBTtype before transmitting the CG-PUSCH, the UE may transmit the CG-PUSCH.The specific PDCCH may be a group common (GC)-PDCCH includingtime/frequency channel occupancy information about the BS. When the UEsucceeds in detecting the PDCCH or a PDCH DRMS, this proposed method maybe applied, or whether a corresponding CG-PUSCH is transmitted may besignaled by a specific field of the GC-PDCCH. While the proposed methodis described in the context of the CG-PUSCH for the convenience ofdescription, the same method is applicable to a UL signal/channel whichmay start to be transmitted without a UL grant, such as aperiodic/semi-persistent SRS and/or a periodic/semi-persistent PUCCH.

The starting time of x may be defined (relatively) from the start or endof a specific PDCCH (or CORESET in which the PDCCH may be transmitted)or as an absolute time (e.g., a frame boundary). The value of x may bepredefined or configured by RMSI and/or another SIB and/or aUE-dedicated RRC signal. Further, a signal/channel of which thedetection/reception triggers a UL channel/signal transmission may beconfigured by a higher-layer signal such as an RRC signal, activationDCI (particularly in the case of CG Type 2 or a semi-persistentSRS/PUCCH), or both, or may be predefined/preagreed in the standards.When the UE fails in receiving/detecting the specific PDCCH in aspecific FFP, the UE may not transmit a UL channel/signal, consideringthat the BS has failed in LBT in the specific FFP. Alternatively, in thecase where an FFP is configured and time resources are configured at anFFP boundary, when the UE succeeds in Cat-2 LBT, the UE may transmit aUL channel/signal in the FFP irrespective of reception/detection of thespecific PDCCH.

Two Cat-2 LBT types may be defined, which should be performed by the UEbefore a UL transmission. In Cat-2 LBT Type 1, for example, the UE mayconsider that a specific UL resource is always valid under anycondition, and transmit a UL signal, upon acquisition of a UE-initiatedCOT by Cat-2 LBT in the configured specific UL resource. That is, the UEmay perform a CAP and transmit a UL signal in the specific UL resource,serving as an initiating device, irrespective of whether the UE hasdetected the specific PDCCH. In another example, in Cat-2 LBT Type 2,the UE may determine the validity of a UL resource according to whethera gNB-initiated COT has been detected and then transmit a UL signal bysharing the COT of the BS, when succeeding in Cat-2 LBT. That is, afterdetermining whether a UL resource is valid depending on whether thespecific PDCCH has been detected, the UE may transmit a UL signal bysharing the COT of the BS, upon success of Cat-2 LBT in a valid ULresource. Alternatively, with a plurality of UL resources configured, aCat-2 LBT type to be used may be configured/indicated on a UL resourcebasis by an RRC signal or RMSI or whether a UL resource is located inthe middle of an FFP or in alignment with the starting time of the FFPmay be configured/indicated on a UL resource basis.

For a UL signal/channel transmittable without a UL grant, such as aCG-PUSCH, a periodic/semi-persistent SRS, or a periodic/semi-persistentPUCCH, the BS may pre-allocate time/frequency resources for transmissionof the UL signal/channel to the UE, and the UE may perform a ULtransmission in the configured resources even without a UL grant. The UEmay be allocated to the resources of the UL channel/signal by ahigher-layer signal such as an RRC signal, a physical-layer signal suchas DCI, or both.

The UE may transmit a UL channel/signal in an FFP configured with the ULchannel/signal transmission by sharing a COT of the BS. Alternatively,in the presence of time resources configured in alignment with an FFPboundary, the UE may autonomously perform Cat-2 LBT in the idle periodof the previous FFP and transmit a UL channel/signal in a correspondingFFP, when determining the channel to be idle. In the former case, whenthe UE attempts to detect or receive the specific PDCCH from the BS inevery FFP and succeeds in detecting or receiving the specific PDCCH, theUE may perform Cat-2 LBT within x ms (or x slots) and upon success ofCat-2 LBT, perform a UL transmission.

A CG-PDCCH may include a bit field that triggers a CG-PUSCH, aperiodic/semi-persistent SRS, or a periodic/semi-persistent PUCCH, orthe UL channel/signal may be transmitted, when a PDCCH DMRS has beensuccessfully detected.

[Proposed method #3] FFPs may be configured separately for the BS andthe UE. Specifically, an FFP of the BS and an FFP of the UE may beconfigured with a gap between them. In the case where the UE isconfigured with a UL signal/channel transmittable without a UL grant,such as a CG-PUSCH and/or a periodic/semi-persistent SRS and/or aperiodic semi-persistent PUCCH, when the UE acquires a UE-initiated COTby Cat-2 LBT in its own FFP, confirming that there is no DL transmissionin the FFP, the UE may transmit the configured UL channel(s)/signal(s).However, when the UE acquires a UE-initiated COT by Cat-2 LBT andconstructs a UL burst with a plurality of signals/channels, a specificchannel/signal may be configured/indicated as a representativechannel/signal. The starting time of the representative channel/signalmay be aligned with the starting time of a configured FFP. The UE mayattempt LBT to the configured representative channel/signal. Whensucceeding in the LBT, the UE may start to transmit the representativechannel/signal. After Cat-2 LBT or Cat-1 LBT, the UE may also transmitthe subsequent other signals/channels according to the length of the gapbetween transmissions. If Cat-1 LBT is applied, a predefined orindicated/configured limit may be imposed on the transmission durationof a UL transmission subsequent to the LBT.

A lower priority may be assigned to a UL signal/channel of which thetransmission may start without a UL grant, such as a CG-PUSCH and/or aperiodic/semi-persistent SRS and/or a periodic/semi-persistent PUCCH,unlike a UL grant-based UL transmission than a DL transmission from theBS, so that the UL signal/channel may be transmitted in an FFP free of aDL transmission. When the FFP of the UE is configured to follow the FFPof the BS in time with a gap between them, an idle period in which LBTis performed before a UL signal transmission in the FFP of the UE islocated in the middle of the FFP of the BS. Therefore, when confirmingthe absence of any DL transmission in the FFP, the UE may perform the ULtransmission. That is, when the BS is confirmed as not using the FFP,the UE transmits the UL signal/channel transmittable without a UL grant,in preconfigured resources.

Referring to FIG. 11, when an FFP of a UE is configured to follow an FFPof a BS in time with a gap of lms between the FFPs, an idle period inwhich the UE performs LBT is located after the starting time of the FFPof the BS. Because a transmission in an FBE is allowed to start only atan FFP boundary, the UE may transmit a UL channel/signal transmittablewithout a UL grant, determining that success of LBT of the UE isattributed to the absence of a DL transmission from the BS in the FFP.

[Proposed method #4] On a primacy cell (PCell), the BS as an initiatingdevice provides, to the UE, information about a channel access mode (theFBE or LBE mode), an FFP of the BS, and the starting position of theFFP, for an FBE operation by a higher-layer signal (e.g., SIB), and whenadding a secondary cell (SCell) for carrier aggregation (CA), configuresthe channel access mode and/or FBE-related parameters of the SCell.

(1) Each time an SCell is added, information about the channel accessmode and/or FBE-related information of the SCell (the channel accessmode and/or an FFP and the starting position of the FFP) may beconfigured by a higher-layer signal, irrespective of the operation modeof the PCell.

(2) In the case where when an SCell is added, information about thechannel access mode and/or FBE-related information of the SCell (thechannel access mode and/or an FFP and the starting position of the FFP)is not configured by a higher-layer signal, the SCell may be operated inthe same channel access mode as that of the PCell. (Particularly whenthe PCell is operated in the FBE mode, the SCell may be operated on theassumption that FBE-related parameters of the SCell are also identicalto those of the PCell).

(3) In the case of intra-band CA and an FBE-mode PCell, an SCell may beoperated in the FBE mode with the same FFP parameters as those of thePCell. In the case of inter-band CA and an FBE-mode PCell, an SCell maybe operated according to a channel access mode and/or FBE-relatedparameters configured by a higher-layer signal, or when a channel accessmode is not configured by a higher-layer signal, the SCell may beoperated in the same channel access mode as that of the PCell.(Particularly when the PCell is operated in the FBE mode, the SCell maybe operated on the assumption that FBE-related parameters of the SCellare also identical to those of the PCell).

(4) When FFP parameters are configured together with the channel accessmode of a PCell or an SCell as the LBE mode by a higher-layer signal,the UE may perform LBT based on the configured FFP parameters,considering that the UE may operate as an initiating device. When the UEsucceeds in the LBT, the UE may perform a UL transmission.

(5) In a dual connectivity situation, the above-described methods of (1)to (4) may be applied to CA between a primary secondary cell (PSCell)and an SCell or to the PSCell on the PCell.

(6) If the PCell is an L-Cell, the channel access mode and/or FFPparameters of the SCell may be configured by a higher-layer signal. Whenthe channel access mode and/or FFP parameters of the SCell are notconfigured by a higher-layer signal, the UE may operate on theassumption of the LBE mode as a default mode. The CA situation isexemplary, and the channel access mode of a serving cell or a cell to beaccessed by the UE may be configured by a higher-layer signalirrespective of a PCell or an SCell. However, if the channel access modeof a serving cell or a cell to be accessed by the UE is not configuredby a higher-layer signal, the UE may operate on the assumption of theLBE mode. For example, when an SIB received by the UE does not includeinformation about a channel access mode, the UE may operate in the LBEmode, considering that the serving cell/the cell to be accessed operatesin the LBE mode. Specifically, when the UE operating in the LBE mode hastransmission data, the UE may transmit the data based on the result of aCAP. When the UE operates in the LBE mode, the CAP may include a randombackoff-based CAP (e.g., Type 1 CAP).

The above operations are all for UL operations. When a cell is added,the operations may be applied to a cell configured with a UL operation.

The BS or cell may operate in the LBE mode or the FBE mode. Informationabout the operation mode of the cell, that is, the channel access modeof the cell and FBE-related parameters (an FFP, the starting position ofthe FFP, and so on) for an FBE operation may be transmitted in ahigher-layer signal such as an SIB. Further, when an SCell is added fora CA operation, the SCell may also be operated in the LBE mode or theFBE mode, and thus the channel access mode and/or FBE-related parametersof the SCell may be signaled to the UE by a higher-layer signal. Eachtime an SCell is added, the channel access mode and/or FBE-relatedparameters of the SCell may be configured for the UE by a higher-layersignals as in the method of (1). That is, although the PCell is operatedin the LBE mode, when an SCell is added with its channel access modeconfigured as the FBE mode by a higher-layer signal, the SCell may beoperated in the FBE mode based on the configured FBE-related parameters.

When an SCell is added, the channel access mode or FBE-relatedparameters of the SCell may not be configured by a higher-layer signal.In this case, the SCell may always be operated in the same operationmode and parameters as the channel access mode and/or FBE-relatedparameters of the PCell as in the method of (2). That is, when the PCellis operated in the FBE mode and an SCell is added without aconfiguration from a higher-layer signal, the SCell may be operated inthe FBE mode with the same FBE-related parameters as those of the PCell.When the PCell is operated in the LBE mode, the SCell may also beoperated in the LBE mode.

The SCell may be operated in different channel access modes inintra-band CA and inter-band CA. Specifically, the SCell may always beoperated in the channel access mode and/or FBE-related parameters of thePCell in intra-band CA. In inter-band CA, the SCell may be operateddifferently from the PCell depending on whether the channel access modeand/or 1-BE-related parameters of the SCell are or are not configured bya higher-layer signal. In the former case, the SCell may be operated inthe channel access mode configured by the higher-layer signal, whereasin the latter case, the SCell may be operated in the channel access modeof the PCell and/or with the FBE-related parameters of the PCell,similarly to in intra-band CA.

In the case where despite configuration of the LBE mode as the channelaccess mode of the PCell or the SCell by a higher-layer signal,FBE-related parameters (an FFP, the starting position of the FFP, and soon) are also configured as in the method of (4), the UE may perform LBTwithout a grant from the BS based on the configured FBE-relatedparameters, considering that the operation mode is the FBE mode in whichthe UE may serve as an initiating device. When succeeding in the LBT,the UE may perform a UL transmission.

While operations in the presence and absence of a configuration of achannel access mode and parameters required for an FBE operation in a CAsituation between a PCell and an SCell have been described in themethods of (1) to (4), each method of (1) to (4) may also be applied toCA between a PCell and an SCell in a dual connectivity situation as inthe method of (5).

If the PCell is an L-cell, the channel access mode and/oroperation-related parameters of the SCell may be configured by ahigher-layer signal. Otherwise, the SCell may be operated in the LBEmode as a default channel access mode.

[Proposed method #5] When the BS allocates CG resources to a specificCC/cell, the BS configures/indicates whether all or some of thefollowing NR-U CG features are used for/to a UE by a higher-layer signalsuch as an RRC signal, a physical-layer signal such as DCI, or both.

(1) An HARQ process ID linked to a slot index is not determined.Instead, the UE selects one of HARQ process IDs configured by a CG andtransmits the selected HARQ process ID.

(2) A CG-DFI is monitored to receive a feedback of the result ofdecoding a transmitted CG-PUSCH in the CG-DFI. In the absence ofretransmission scheduling through a UL grant or a feedback such as a DFIduring a configured specific time (or slot duration), the CG-PUSCH isautomatically retransmitted in CG resources.

(3) Each time a CG-PUSCH is transmitted, information such as an HARQprocess ID, a new data indication (NDI), and an RV is also transmittedin CG-UCI.

The above operations are also applicable when the CC/cell is operated inthe FBE mode, and whether to use all or some individual ones of thefeatures may be signaled by RRC signaling. The use or non-use of thefeatures may be determined according to whether the UE is configured asan initiating device or a responding device in a cell/CC configured withthe FBE mode.

Because LBT is involved in all transmissions and LBT failure makestransmission impossible in view of the nature of an unlicensed band, theabove features slightly different from Type 1 CG and Type 2 CG of Rel-15have been introduced to an NR-U CG. However, it may be inefficient orinappropriate to perform a CG transmission using the above NR-U featuresas they are according to the channel access mode of an unlicensed band,for example, in spite of operation in the unlicensed band for a CC/celloperated in the FBE mode.

Accordingly, the BS may additionally configure/indicate whether to useall or some of the NR-U CG features described above in (1), (2), and (3)for/to the UE by a higher-layer signal such as an RRC signal, aphysical-layer signal such as DCI, or both, while providing the channelaccess mode and/or FBE-related parameters of an unlicensed CC/cell by ahigher-layer signal. A CG may adopt the scheme of determining an HARQprocess ID linked to a slot index for a CC/cell configured with non-useof the feature of (1), similarly to Rel-15. For a CC/cell configuredwith non-use of the feature of (2), the UE may not monitor a CG-DFI and,in the absence of a feedback, consider that a CG-PUSCH transmission issuccessful. Further, when the UE is configured/indicated not to use thefeature of (3), the UE may not transmit CG-UCI each time it transmits aCG-PUSCH.

FIGS. 12 and 13 are diagrams illustrating a signal transmission processaccording to an embodiment of the present disclosure.

Referring to FIGS. 12 and 13, a UE receives a higher-layer signal (e.g.,system information) from a BS (S1210 and S1310). The UE may acquire achannel access mode based on the system information (S1220). In anunlicensed band applicable to the present disclosure, two types ofchannel access modes, first and second modes may be supported. The firstmode may correspond to the afore-described LBE mode, and the second modemay correspond to the afore-described FBE mode. The UE may perform a CAPbased on the channel access mode (S1230 and S1320), and transmit a ULsignal based on the result of the CAP (S1240 and S1330).

The UE may perform different CAP types when the UE operates in the firstmode and the second mode. For example, when the UE operates in the firstmode, CAP types available for the UE include a random backoff-based CAP(e.g., Cat-4). Further, when the UE operates in the first mode, the UEmay perform a non-random backoff-based CAP. That is, when the UEdetermines a channel to be idle by performing channel sensing for apredetermined first time period, the UE may transmit a UL signal. Thefirst time period may be, for example, 25 us or 16 us. For example, whenthe UE operates in the second mode, a CAP type available for the UE maybe a non-random backoff-based CAP. That is, when the UE determines achannel to be idle by performing channel sensing for a predeterminedsecond time period in the idle period of an FFP, the UE may transmit aUL signal. The second time period may be, for example, 9 us.

The UE may operate according to a channel access mode indicated by thesystem information. For example, when the channel access mode isindicated as the first mode by the system information, the UE mayoperate in the first mode. Therefore, the UE may perform one of the CAPtypes supported by the first mode before a UL signal transmission. Whenthe channel access mode is indicated as the second mode by the systeminformation, the UE may operate in the second mode. Therefore, the UEmay perform a CAP according to the CAP type supported by the second modebefore a UL signal transmission. When the information about a channelaccess mode is not included in the system information, the UE mayoperate in the first mode, assuming the first mode to be a default mode.

For example, the UL signal may include a PRACH of proposed method #1.

For example, the UL signal may include a UL signal (e.g., a CG-PUSCH)which does not require a UL grant, described in proposed method #3.

Unless contradicting with each other, all of the afore-describedproposed methods may be implemented in combination.

The various descriptions, functions, procedures, proposals, methods,and/or operation flowcharts of the present disclosure described hereinmay be applied to, but not limited to, various fields requiring wirelesscommunication/connectivity (e.g., 5G) between devices.

More specific examples will be described below with reference to thedrawings. In the following drawings/description, like reference numeralsdenote the same or corresponding hardware blocks, software blocks, orfunction blocks, unless otherwise specified.

FIG. 14 illustrates a communication system 1 applied to the presentdisclosure.

Referring to FIG. 14, the communication system 1 applied to the presentdisclosure includes wireless devices, BSs, and a network. A wirelessdevice is a device performing communication using radio accesstechnology (RAT) (e.g., 5G NR (or New RAT) or LTE), also referred to asa communication/radio/5G device. The wireless devices may include, notlimited to, a robot 100 a, vehicles 100 b-1 and 100 b-2, an extendedreality (XR) device 100 c, a hand-held device 100 d, a home appliance100 e, an IoT device 100 f, and an artificial intelligence (AI)device/server 400. For example, the vehicles may include a vehiclehaving a wireless communication function, an autonomous driving vehicle,and a vehicle capable of vehicle-to-vehicle (V2V) communication. Herein,the vehicles may include an unmanned aerial vehicle (UAV) (e.g., adrone). The XR device may include an augmented reality (AR)/virtualreality (VR)/mixed reality (MR) device and may be implemented in theform of a head-mounted device (HMD), a head-up display (HUD) mounted ina vehicle, a television (TV), a smartphone, a computer, a wearabledevice, a home appliance, a digital signage, a vehicle, a robot, and soon. The hand-held device may include a smartphone, a smartpad, awearable device (e.g., a smartwatch or smartglasses), and a computer(e.g., a laptop). The home appliance may include a TV, a refrigerator, awashing machine, and so on. The IoT device may include a sensor, asmartmeter, and so on. For example, the BSs and the network may beimplemented as wireless devices, and a specific wireless device 200 amay operate as a BS/network node for other wireless devices.

The wireless devices 100 a to 100 f may be connected to the network 300via the BSs 200. An AI technology may be applied to the wireless devices100 a to 100 f, and the wireless devices 100 a to 100 f may be connectedto the AI server 400 via the network 300. The network 300 may beconfigured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g.,NR) network. Although the wireless devices 100 a to 100 f maycommunicate with each other through the BSs 200/network 300, thewireless devices 100 a to 100 f may perform direct communication (e.g.,sidelink communication) with each other without intervention of theBSs/network. For example, the vehicles 100 b-1 and 100 b-2 may performdirect communication (e.g. V2V/vehicle-to-everything (V2X)communication). The IoT device (e.g., a sensor) may perform directcommunication with other IoT devices (e.g., sensors) or other wirelessdevices 100 a to 100 f.

Wireless communication/connections 150 a, 150 b, and 150 c may beestablished between the wireless devices 100 a to 100 f/BS 200 andbetween the BSs 200. Herein, the wireless communication/connections maybe established through various RATs (e.g., 5G NR) such as UL/DLcommunication 150 a, sidelink communication 150 b (or, D2Dcommunication), or inter-BS communication (e.g. relay or integratedaccess backhaul (IAB)). Wireless signals may be transmitted and receivedbetween the wireless devices, between the wireless devices and the BSs,and between the BSs through the wireless communication/connections 150a, 150 b, and 150 c. For example, signals may be transmitted and receivedon various physical channels through the wirelesscommunication/connections 150 a, 150 b and 150 c. To this end, at leasta part of various configuration information configuring processes,various signal processing processes (e.g., channel encoding/decoding,modulation/demodulation, and resource mapping/demapping), and resourceallocation processes, for transmitting/receiving wireless signals, maybe performed based on the various proposals of the present disclosure.

FIG. 15 illustrates wireless devices applicable to the presentdisclosure.

Referring to FIG. 15, a first wireless device 100 and a second wirelessdevice 200 may transmit wireless signals through a variety of RATs(e.g., LTE and NR). {The first wireless device 100 and the secondwireless device 200} may correspond to {the wireless device 100 x andthe BS 200} and/or {the wireless device 100 x and the wireless device100 x} of FIG. 14.

The first wireless device 100 may include one or more processors 102 andone or more memories 104, and further include one or more transceivers106 and/or one or more antennas 108. The processor(s) 102 may controlthe memory(s) 104 and/or the transceiver(s) 106 and may be configured toimplement the descriptions, functions, procedures, proposals, methods,and/or operation flowcharts disclosed in this document. For example, theprocessor(s) 102 may process information in the memory(s) 104 togenerate first information/signals and then transmit wireless signalsincluding the first information/signals through the transceiver(s) 106.The processor(s) 102 may receive wireless signals including secondinformation/signals through the transceiver(s) 106 and then storeinformation obtained by processing the second information/signals in thememory(s) 104. The memory(s) 104 may be connected to the processor(s)102 and may store various pieces of information related to operations ofthe processor(s) 102. For example, the memory(s) 104 may store softwarecode including instructions for performing all or a part of processescontrolled by the processor(s) 102 or for performing the descriptions,functions, procedures, proposals, methods, and/or operation flowchartsdisclosed in this document. The processor(s) 102 and the memory(s) 104may be a part of a communication modem/circuit/chip designed toimplement RAT (e.g., LTE or NR). The transceiver(s) 106 may be connectedto the processor(s) 102 and transmit and/or receive wireless signalsthrough the one or more antennas 108. Each of the transceiver(s) 106 mayinclude a transmitter and/or a receiver. The transceiver(s) 106 may beinterchangeably used with radio frequency (RF) unit(s). In the presentdisclosure, the wireless device may be a communicationmodem/circuit/chip.

The second wireless device 200 may include one or more processors 202and one or more memories 204, and further include one or moretransceivers 206 and/or one or more antennas 208. The processor(s) 202may control the memory(s) 204 and/or the transceiver(s) 206 and may beconfigured to implement the descriptions, functions, procedures,proposals, methods, and/or operation flowcharts disclosed in thisdocument. For example, the processor(s) 202 may process information inthe memory(s) 204 to generate third information/signals and thentransmit wireless signals including the third information/signalsthrough the transceiver(s) 206. The processor(s) 202 may receivewireless signals including fourth information/signals through thetransceiver(s) 106 and then store information obtained by processing thefourth information/signals in the memory(s) 204. The memory(s) 204 maybe connected to the processor(s) 202 and store various pieces ofinformation related to operations of the processor(s) 202. For example,the memory(s) 204 may store software code including instructions forperforming all or a part of processes controlled by the processor(s) 202or for performing the descriptions, functions, procedures, proposals,methods, and/or operation flowcharts disclosed in this document. Theprocessor(s) 202 and the memory(s) 204 may be a part of a communicationmodem/circuit/chip designed to implement RAT (e.g., LTE or NR). Thetransceiver(s) 206 may be connected to the processor(s) 202 and transmitand/or receive wireless signals through the one or more antennas 208.Each of the transceiver(s) 206 may include a transmitter and/or areceiver. The transceiver(s) 206 may be interchangeably used with RFunit(s). In the present disclosure, the wireless device may be acommunication modem/circuit/chip.

Now, hardware elements of the wireless devices 100 and 200 will bedescribed in greater detail. One or more protocol layers may beimplemented by, not limited to, one or more processors 102 and 202. Forexample, the one or more processors 102 and 202 may implement one ormore layers (e.g., functional layers such as physical (PHY), mediumaccess control (MAC), radio link control (RLC), packet data convergenceprotocol (PDCP), RRC, and service data adaptation protocol (SDAP)). Theone or more processors 102 and 202 may generate one or more protocoldata units (PDUs) and/or one or more service data Units (SDUs) accordingto the descriptions, functions, procedures, proposals, methods, and/oroperation flowcharts disclosed in this document. The one or moreprocessors 102 and 202 may generate messages, control information, data,or information according to the descriptions, functions, procedures,proposals, methods, and/or operation flowcharts disclosed in thisdocument and provide the messages, control information, data, orinformation to one or more transceivers 106 and 206. The one or moreprocessors 102 and 202 may generate signals (e.g., baseband signals)including PDUs, SDUs, messages, control information, data, orinformation according to the descriptions, functions, procedures,proposals, methods, and/or operation flowcharts disclosed in thisdocument and provide the generated signals to the one or moretransceivers 106 and 206. The one or more processors 102 and 202 mayreceive the signals (e.g., baseband signals) from the one or moretransceivers 106 and 206 and acquire the PDUs, SDUs, messages, controlinformation, data, or information according to the descriptions,functions, procedures, proposals, methods, and/or operation flowchartsdisclosed in this document.

The one or more processors 102 and 202 may be referred to ascontrollers, microcontrollers, microprocessors, or microcomputers. Theone or more processors 102 and 202 may be implemented by hardware,firmware, software, or a combination thereof. For example, one or moreapplication specific integrated circuits (ASICs), one or more digitalsignal processors (DSPs), one or more digital signal processing devices(DSPDs), one or more programmable logic devices (PLDs), or one or morefield programmable gate arrays (FPGAs) may be included in the one ormore processors 102 and 202. The descriptions, functions, procedures,proposals, methods, and/or operation flowcharts disclosed in thisdocument may be implemented using firmware or software, and the firmwareor software may be configured to include the modules, procedures, orfunctions. Firmware or software configured to perform the descriptions,functions, procedures, proposals, methods, and/or operation flowchartsdisclosed in this document may be included in the one or more processors102 and 202 or may be stored in the one or more memories 104 and 204 andexecuted by the one or more processors 102 and 202. The descriptions,functions, procedures, proposals, methods, and/or operation flowchartsdisclosed in this document may be implemented using firmware or softwarein the form of code, an instruction, and/or a set of instructions.

The one or more memories 104 and 204 may be connected to the one or moreprocessors 102 and 202 and store various types of data, signals,messages, information, programs, code, instructions, and/or commands.The one or more memories 104 and 204 may be configured to includeread-only memories (ROMs), random access memories (RAMs), electricallyerasable programmable read-only memories (EPROMs), flash memories, harddrives, registers, cash memories, computer-readable storage media,and/or combinations thereof. The one or more memories 104 and 204 may belocated at the interior and/or exterior of the one or more processors102 and 202. The one or more memories 104 and 204 may be connected tothe one or more processors 102 and 202 through various technologies suchas wired or wireless connection.

The one or more transceivers 106 and 206 may transmit user data, controlinformation, and/or wireless signals/channels, mentioned in the methodsand/or operation flowcharts of this document, to one or more otherdevices. The one or more transceivers 106 and 206 may receive user data,control information, and/or wireless signals/channels, mentioned in thedescriptions, functions, procedures, proposals, methods, and/oroperation flowcharts disclosed in this document, from one or more otherdevices. For example, the one or more transceivers 106 and 206 may beconnected to the one or more processors 102 and 202 and transmit andreceive wireless signals. For example, the one or more processors 102and 202 may perform control so that the one or more transceivers 106 and206 may transmit user data, control information, or wireless signals toone or more other devices. The one or more processors 102 and 202 mayperform control so that the one or more transceivers 106 and 206 mayreceive user data, control information, or wireless signals from one ormore other devices. The one or more transceivers 106 and 206 may beconnected to the one or more antennas 108 and 208 and the one or moretransceivers 106 and 206 may be configured to transmit and receive userdata, control information, and/or wireless signals/channels, mentionedin the descriptions, functions, procedures, proposals, methods, and/oroperation flowcharts disclosed in this document, through the one or moreantennas 108 and 208. In this document, the one or more antennas may bea plurality of physical antennas or a plurality of logical antennas(e.g., antenna ports). The one or more transceivers 106 and 206 mayconvert received wireless signals/channels from RF band signals intobaseband signals in order to process received user data, controlinformation, and wireless signals/channels using the one or moreprocessors 102 and 202. The one or more transceivers 106 and 206 mayconvert the user data, control information, and wirelesssignals/channels processed using the one or more processors 102 and 202from the baseband signals into the RF band signals. To this end, the oneor more transceivers 106 and 206 may include (analog) oscillators and/orfilters.

FIG. 16 illustrates another example of a wireless device applied to thepresent disclosure. The wireless device may be implemented in variousforms according to a use case/service (refer to FIG. 14).

Referring to FIG. 16, wireless devices 100 and 200 may correspond to thewireless devices 100 and 200 of FIG. 14 and may be configured to includevarious elements, components, units/portions, and/or modules. Forexample, each of the wireless devices 100 and 200 may include acommunication unit 110, a control unit 120, a memory unit 130, andadditional components 140. The communication unit 110 may include acommunication circuit 112 and transceiver(s) 114. For example, thecommunication circuit 112 may include the one or more processors 102 and202 and/or the one or more memories 104 and 204 of FIG. 15. For example,the transceiver(s) 114 may include the one or more transceivers 106 and206 and/or the one or more antennas 108 and 208 of FIG. 15. The controlunit 120 is electrically connected to the communication unit 110, thememory 130, and the additional components 140 and provides overallcontrol to the wireless device. For example, the control unit 120 maycontrol an electric/mechanical operation of the wireless device based onprograms/code/instructions/information stored in the memory unit 130.The control unit 120 may transmit the information stored in the memoryunit 130 to the outside (e.g., other communication devices) via thecommunication unit 110 through a wireless/wired interface or store, inthe memory unit 130, information received through the wireless/wiredinterface from the outside (e.g., other communication devices) via thecommunication unit 110.

The additional components 140 may be configured in various mannersaccording to type of the wireless device. For example, the additionalcomponents 140 may include at least one of a power unit/battery,input/output (I/O) unit, a driving unit, and a computing unit. Thewireless device may be implemented in the form of, not limited to, therobot (100 a of FIG. 14), the vehicles (100 b-1 and 100 b-2 of FIG. 14),the XR device (100 c of FIG. 14), the hand-held device (100 d of FIG.14), the home appliance (100 e of FIG. 14), the IoT device (100 f ofFIG. 14), a digital broadcasting terminal, a hologram device, a publicsafety device, an MTC device, a medical device, a FinTech device (or afinance device), a security device, a climate/environment device, the AIserver/device (400 of FIG. 14), the B Ss (200 of FIG. 14), a networknode, or the like. The wireless device may be mobile or fixed accordingto a use case/service.

In FIG. 16, all of the various elements, components, units/portions,and/or modules in the wireless devices 100 and 200 may be connected toeach other through a wired interface or at least a part thereof may bewirelessly connected through the communication unit 110. For example, ineach of the wireless devices 100 and 200, the control unit 120 and thecommunication unit 110 may be connected by wire and the control unit 120and first units (e.g., 130 and 140) may be wirelessly connected throughthe communication unit 110. Each element, component, unit/portion,and/or module in the wireless devices 100 and 200 may further includeone or more elements. For example, the control unit 120 may beconfigured with a set of one or more processors. For example, thecontrol unit 120 may be configured with a set of a communication controlprocessor, an application processor, an electronic control unit (ECU), agraphical processing unit, and a memory control processor. In anotherexample, the memory 130 may be configured with a RAM, a dynamic RAM(DRAM), a ROM, a flash memory, a volatile memory, a non-volatile memory,and/or a combination thereof.

FIG. 17 illustrates a vehicle or an autonomous driving vehicle appliedto the present disclosure. The vehicle or autonomous driving vehicle maybe implemented as a mobile robot, a car, a train, a manned/unmannedaerial vehicle (AV), a ship, or the like.

Referring to FIG. 17, a vehicle or autonomous driving vehicle 100 mayinclude an antenna unit 108, a communication unit 110, a control unit120, a driving unit 140 a, a power supply unit 140 b, a sensor unit 140c, and an autonomous driving unit 140 d. The antenna unit 108 may beconfigured as a part of the communication unit 110. The blocks110/130/140 a to 140 d correspond to the blocks 110/130/140 of FIG. 16,respectively.

The communication unit 110 may transmit and receive signals (e.g., dataand control signals) to and from external devices such as othervehicles, BSs (e.g., gNBs and road side units), and servers. The controlunit 120 may perform various operations by controlling elements of thevehicle or the autonomous driving vehicle 100. The control unit 120 mayinclude an ECU. The driving unit 140 a may enable the vehicle or theautonomous driving vehicle 100 to drive on a road. The driving unit 140a may include an engine, a motor, a powertrain, a wheel, a brake, asteering device, and so on. The power supply unit 140 b may supply powerto the vehicle or the autonomous driving vehicle 100 and include awired/wireless charging circuit, a battery, and so on. The sensor unit140 c may acquire information about a vehicle state, ambient environmentinformation, user information, and so on. The sensor unit 140 c mayinclude an inertial measurement unit (IMU) sensor, a collision sensor, awheel sensor, a speed sensor, a slope sensor, a weight sensor, a headingsensor, a position module, a vehicle forward/backward sensor, a batterysensor, a fuel sensor, a tire sensor, a steering sensor, a temperaturesensor, a humidity sensor, an ultrasonic sensor, an illumination sensor,a pedal position sensor, and so on. The autonomous driving unit 140 dmay implement technology for maintaining a lane on which the vehicle isdriving, technology for automatically adjusting speed, such as adaptivecruise control, technology for autonomously driving along a determinedpath, technology for driving by automatically setting a route if adestination is set, and the like.

For example, the communication unit 110 may receive map data, trafficinformation data, and so on from an external server. The autonomousdriving unit 140 d may generate an autonomous driving route and adriving plan from the obtained data. The control unit 120 may controlthe driving unit 140 a such that the vehicle or autonomous drivingvehicle 100 may move along the autonomous driving route according to thedriving plan (e.g., speed/direction control). During autonomous driving,the communication unit 110 may aperiodically/periodically acquire recenttraffic information data from the external server and acquiresurrounding traffic information data from neighboring vehicles. Duringautonomous driving, the sensor unit 140 c may obtain information about avehicle state and/or surrounding environment information. The autonomousdriving unit 140 d may update the autonomous driving route and thedriving plan based on the newly obtained data/information. Thecommunication unit 110 may transfer information about a vehicleposition, the autonomous driving route, and/or the driving plan to theexternal server. The external server may predict traffic informationdata using AI technology based on the information collected fromvehicles or autonomous driving vehicles and provide the predictedtraffic information data to the vehicles or the autonomous drivingvehicles.

The embodiments of the present disclosure described above arecombinations of elements and features of the present disclosure. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent disclosure may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent disclosure may be rearranged. Some constructions of any oneembodiment may be included in another embodiment and may be replacedwith corresponding constructions of another embodiment. It is obvious tothose skilled in the art that claims that are not explicitly cited ineach other in the appended claims may be presented in combination as anembodiment of the present disclosure or included as a new claim by asubsequent amendment after the application is filed.

The embodiments of the present disclosure have been described above,focusing on the signal transmission and reception relationship between aUE and a BS. The signal transmission and reception relationship isextended to signal transmission and reception between a UE and a relayor between a BS and a relay in the same manner or a similar manner Aspecific operation described as performed by a BS may be performed by anupper node of the BS. Namely, it is apparent that, in a networkcomprised of a plurality of network nodes including a BS, variousoperations performed for communication with a UE may be performed by theBS, or network nodes other than the BS. The term BS may be replaced withthe term fixed station, Node B, enhanced Node B (eNode B or eNB), accesspoint, and so on. Further, the term UE may be replaced with the termterminal, mobile station (MS), mobile subscriber station (MSS), and soon.

Those skilled in the art will appreciate that the present disclosure maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent disclosure. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of thedisclosure should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein.

INDUSTRIAL APPLICABILITY

The present disclosure may be used in a UE, a BS, or other devices in amobile communication system.

1. A method of a user equipment (UE) in a wireless communication system,the method comprising: receiving system information; acquiring a channelaccess mode based on the system information; performing a channel accessprocedure (CAP) based on the channel access mode; and transmitting anuplink signal based on a result of the CAP, wherein the channel accessmode includes a first mode and a second mode, a CAP type of the firstmode is difference from a CAP type of the second mode, and the acquiredchannel access mode is i) a channel access mode indicated by the systeminformation between the first mode and the second mode based on thesystem information including information about the channel access mode,or ii) the first mode based on the system information not including theinformation about the channel access mode.
 2. The method according toclaim 1, wherein the CAP type of the first mode includes a randombackoff-based CAP.
 3. The method according to claim 2, wherein thesecond mode is a mode in which the CAP and the signal transmission areperformed in a period of a specific length based on a structure ofperiodically repeating the period of the specific length.
 4. The methodaccording to claim 3, wherein the CAP type of the first mode furtherincludes a CAP in which it is determined whether a channel is idleduring a predetermined first time period, and the CAP type of the secondmode is a CAP in which it is determined whether a channel is idle for apredetermined second time period.
 5. The method according to claim 4,wherein the length of the first time period is larger than the length ofthe second time period.
 6. The method according to claim 4, wherein thesecond time period is included in the period of the specific length. 7.The method according to claim 3, wherein the UL signal includes aphysical random access channel (PRACH), and based on an RACH occasion(RO) being configured as a boundary of the period of the specificlength, the PRACH is transmitted in the RO based on the result of theCAP regardless of whether a downlink signal has been detected in theperiod of the specific length.
 8. The method according to claim 3,wherein the uplink signal includes an uplink signal not including anuplink grant, the period of the specific length is configured for eachof a base station (BS) and the UE, and the uplink signal is transmittedin the period of the specific length based on the result of the CAP,based on a downlink signal not being received in the period of thespecific length configured for the UE.
 9. The method according to claim1, wherein the uplink signal is transmitted in an unlicensed band.
 10. Auser equipment (UE) in a wireless communication system, the UEcomprising: at least one transceiver; at least one processor; and atleast one computer memory operatively coupled to the at least onetransceiver and at least one processor and, when executed, causing theat least one transceiver and at least one processor to performoperations, wherein the operations include: receiving systeminformation; acquiring a channel access mode based on the systeminformation; performing a channel access procedure (CAP) based on thechannel access mode; and transmitting an uplink signal based on a resultof the CAP, and wherein the channel access mode includes a first modeand a second mode, a CAP type of the first mode is difference from a CAPtype of the second mode, and the acquired channel access mode is i) achannel access mode indicated by the system information between thefirst mode and the second mode based on the system information includinginformation about the channel access mode, or ii) the first mode basedon the system information not including the information about thechannel access mode.
 11. The UE according to claim 10, wherein the CAPtype of the first mode includes a random backoff-based CAP.
 12. The UEaccording to claim 11, wherein the second mode is a mode in which theCAP and the signal transmission are performed in a period of a specificlength based on a structure of periodically repeating the period of thespecific length.
 13. The UE according to claim 12, wherein the CAP typeof the first mode further includes a CAP in which it is determinedwhether a channel is idle during a predetermined first time period, andthe CAP type of the second mode is a CAP in which it is determinedwhether a channel is idle for a predetermined second time period. 14.The UE according to claim 13, wherein the length of the first timeperiod is larger than the length of the second time period.
 15. The UEaccording to claim 10, wherein the UE includes an autonomous drivingvehicle communicable with at least one of a network or anotherautonomous driving vehicle other than the UE.
 16. An apparatus for auser equipment (UE), the apparatus comprising: at least one processor;and at least one computer memory operatively coupled to the at least oneprocessor and, when executed, causing the at least one processor toperform operations, wherein the operations include: receiving systeminformation; acquiring a channel access mode based on the systeminformation; performing a channel access procedure (CAP) based on thechannel access mode; and transmitting an uplink signal based on a resultof the CAP, and wherein the channel access mode includes a first modeand a second mode, a CAP type of the first mode is difference from a CAPtype of the second mode, and the acquired channel access mode is i) achannel access mode indicated by the system information between thefirst mode and the second mode based on the system information includinginformation about the channel access mode, or ii) the first mode basedon the system information not including the information about thechannel access mode.